Biaxially oriented polyester film, laminate, and packaging container

Abstract

To provide: a biaxially oriented polyester film that can reduce environmental impact, can reduce a yellow tint, and can inhibit or reduce film rupture that may occur during drawing; a laminate comprising the biaxially oriented polyester film; and a packaging container comprising the laminate.SOLUTION: A biaxially oriented polyester film 8 contains a chemically recycled polyester. In a molecular weight distribution curve obtained by gel permeation chromatography of the biaxially oriented polyester film 8, the area ratio of a region having molecular weight of 1000 or less is from 1.9% to 5.5%, inclusive, of the total peak area. The chemically recycled polyester can reduce environmental impact. The area ratio being less than or equal to 5.5% can reduce a yellow tint. The area ratio being greater than or equal to 1.9% can prevent the stress during drawing in a manufacturing process (i.e., the drawing stress) from excessively increasing, and thus can inhibit or reduce film rupture that may occur during the drawing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a biaxially oriented polyester film, a laminate, and a packaging container. [Background technology]

[0002] Polyesters, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), are thermoplastic resins with excellent heat resistance and mechanical properties, and are used in a wide range of fields including plastic films, electronics, energy, packaging materials, and automobiles. In particular, biaxially oriented polyester films are widely used in industrial and packaging fields because they offer an excellent balance between mechanical properties (i.e., mechanical strength), heat resistance, dimensional stability, chemical resistance, optical properties, and cost.

[0003] In recent years, with the growing demand for a circular economy, the use of recycled materials has been increasing in the materials sector. In the case of polyester, recycled PET bottles are being used. It is said that using recycled polyester contributes to CO2 reduction. For these reasons, it is desirable to increase the proportion of recycled polyester used, even slightly.

[0004] For example, Patent Document 1 discloses a biaxially oriented polyester film made using polyester obtained by mechanically recycling PET bottles, i.e., mechanically recycled polyester.

[0005] However, used polyester products such as used PET bottles vary in their level of contamination depending on the contents they were filled with and the storage environment, making it difficult to remove contaminants to a high degree through mechanical recycling.

[0006] In addition, since mechanical recycled polyester contains a relatively large amount of low molecular weight components, products made using mechanical recycled polyester sometimes exhibit a yellowish color.

[0007] By contrast, as a polyester recycled by a method different from mechanical recycling, there is known a polyester obtained by decomposing the polyester contained in used polyester products to the monomer level and then repolymerizing it, that is, chemical recycled polyester (see Patent Documents 3 and 4).

[0008] For example, Patent Document 2 discloses a printed resin film including a polyester film made using chemical recycled polyester and a printing layer.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0010] Chemical recycled polyester is often polymerized to a high molecular weight by solid-phase polymerization so as to be easily formed into PET bottles, and moreover, since low molecular weight components are reduced in the process, the intrinsic viscosity of chemical recycled polyester is often higher than that of polyester for general biaxially oriented polyester films.

[0011] In the process of investigating the use of chemically recycled polyester for the production of biaxially oriented polyester films, rather than for PET bottles, the inventors discovered that films made from chemically recycled polyester are prone to breakage during stretching, and therefore the film formation rate may have to be excessively reduced.

[0012] In response to this, the inventors have discovered an amount of low molecular weight component that can suppress or reduce film breakage that may occur during stretching, and that can also reduce the yellowish tint that biaxially oriented polyester films may exhibit, thereby completing the present invention.

[0013] The present invention aims to provide a biaxially oriented polyester film that can reduce environmental impact, reduce yellowing, and suppress or reduce film breakage that may occur during stretching. The present invention also aims to provide a laminate containing the biaxially oriented polyester film and a packaging container containing the laminate. [Means for solving the problem]

[0014] To solve this problem, the present invention comprises the configuration described in [1] below. [1] Contains chemically recycled polyester, In the molecular weight distribution curve obtained by gel permeation chromatography, the area percentage of the region with a molecular weight of 1000 or less is between 1.9% and 5.5% of the total peak area. Biaxially oriented polyester film. Here, "chemically recycled polyester" refers to polyester obtained by decomposing the polyester contained in used polyester products down to the monomer level and then repolymerizing it.

[0015] [1] states that the biaxially oriented polyester film contains chemically recycled polyester. Here, "the biaxially oriented polyester film contains chemically recycled polyester" means that if the biaxially oriented polyester film contains multiple layers, at least one of the multiple layers contains chemically recycled polyester.

[0016] [1] According to this, the biaxially oriented polyester film contains chemically recycled polyester, thus reducing the environmental impact.

[0017] Furthermore, by limiting the area percentage of the region with a molecular weight of 1,000 or less to 5.5% or less, that is, by setting an upper limit on the content of components with a molecular weight of 1,000 or less (hereinafter sometimes referred to as "low molecular weight components"), the yellowish tint that biaxially oriented polyester films may exhibit can be reduced.

[0018] Furthermore, by ensuring that the area proportion of the region with a molecular weight of 1000 or less is 1.9% or more, that is, by setting a lower limit for the content of low molecular weight components, it is possible to secure a content of low molecular weight components that can act like plasticizers.

[0019] Furthermore, by ensuring that the area proportion of the region with a molecular weight of 1000 or less is 1.9% or more, it is possible to limit the molecular weight of the polyester contained in the biaxially oriented polyester film to a certain extent. This will be explained. Since low molecular weight components are incorporated into the polyester during the polymerization process, the higher the molecular weight of the polyester, the fewer low molecular weight components tend to be, and the lower the molecular weight of the polyester, the more low molecular weight components tend to be. According to [1], since the area proportion of the region with a molecular weight of 1000 or less is 1.9% or more, that is, because a certain amount of low molecular weight components are present, it is possible to limit the molecular weight of the polyester contained in the biaxially oriented polyester film to a certain extent.

[0020] Therefore, it is possible to prevent excessive stress (i.e., tensile stress) during the stretching process in the manufacturing of biaxially oriented polyester film, and as a result, it is possible to suppress or reduce film breakage that may occur during stretching.

[0021] The present invention preferably further comprises the configurations described in [2] and later below.

[0022] [2] A biaxially oriented polyester film as described in [1], wherein the color b* value per 1 μm thickness is 0.067 or less.

[0023] [2] According to this, the yellowish tint that biaxially oriented polyester film may exhibit can be limited. Therefore, for example, when a printed layer is formed on a biaxially oriented polyester film, the influence of the color of the biaxially oriented polyester film on the appearance (i.e., appearance) of the printed layer can be reduced. Also, for example, when a packaging container is made using a biaxially oriented polyester film, the influence of the color of the biaxially oriented polyester film on the appearance of the contents can be reduced.

[0024] [3] The biaxially oriented polyester film according to [1] or [2], wherein the chemical recycled polyester content is 20% by mass or more.

[0025] [3] According to this, the environmental impact can be further reduced.

[0026] [4] A biaxially oriented polyester film as described in any of [1] to [3], Including a sealant layer, Laminated structure.

[0027] [4] According to [4], since the laminate includes a sealant layer, products containing the laminate (e.g., packaging containers) can be manufactured by heat sealing.

[0028] [5] Further including a printed layer, In at least a portion of the laminate, the printed layer, the biaxially oriented polyester film, and the sealant layer are arranged in this order in the thickness direction of the laminate. [4] The laminate described above. Here, the phrase "the printed layer, the biaxially oriented polyester film, and the sealant layer are arranged in this order in the thickness direction of the laminate" is an expression that allows for the presence of other layers between the printed layer and the biaxially oriented polyester film, or between the biaxially oriented polyester film and the sealant layer.

[0029] [5] According to [5], since the laminate includes a printed layer, designs (e.g., letters, patterns, symbols, etc.) can be applied to the laminate or to products containing the laminate (e.g., packaging containers).

[0030] [6] Further including a printed layer, In at least a portion of the laminate, the biaxially oriented polyester film, the printing layer, and the sealant layer are arranged in this order in the thickness direction of the laminate. [4] The laminate described above. Here, the phrase "the biaxially oriented polyester film, the printed layer, and the sealant layer are arranged in this order in the thickness direction of the laminate" is an expression that allows for the presence of other layers between the biaxially oriented polyester film and the printed layer, and between the printed layer and the sealant layer.

[0031] [6] According to [6], since the laminate includes a printed layer, designs (e.g., letters, patterns, symbols, etc.) can be applied to the laminate or to products containing the laminate (e.g., packaging containers).

[0032] [7] A biaxially oriented polyester film as described in any of [1] to [3], Including an adhesive layer, Laminated structure.

[0033] [7] According to [7], since the laminate includes an adhesive layer, products containing the laminate (e.g., packaging containers) can be manufactured by pressurization.

[0034] [8] Further including a printed layer, In at least a portion of the laminate, the printed layer, the biaxially oriented polyester film, and the adhesive layer are arranged in this order in the thickness direction of the laminate. [7] The laminate described above. Here, the phrase "the printed layer, the biaxially oriented polyester film, and the adhesive layer are arranged in this order in the thickness direction of the laminate" is an expression that allows for the presence of other layers between the printed layer and the biaxially oriented polyester film, or between the biaxially oriented polyester film and the adhesive layer.

[0035] [8] According to [8], since the laminate includes a printed layer, designs (e.g., letters, patterns, symbols, etc.) can be applied to the laminate or to products containing the laminate (e.g., packaging containers).

[0036] [9] Further including a printed layer, In at least a portion of the laminate, the biaxially oriented polyester film, the printing layer, and the adhesive layer are arranged in this order in the thickness direction of the laminate. [7] The laminate described above. Here, the phrase "the biaxially oriented polyester film, the printed layer, and the adhesive layer are arranged in this order in the thickness direction of the laminate" is an expression that allows for the presence of other layers between the biaxially oriented polyester film and the printed layer, and between the printed layer and the adhesive layer.

[0037] [9] According to [9], since the laminate includes a printed layer, designs (e.g., letters, patterns, symbols, etc.) can be applied to the laminate or to products containing the laminate (e.g., packaging containers).

[0038]

[10] A packaging container comprising a laminate as described in any of [4] to [9]. [Effects of the Invention]

[0039] According to the present invention, it is possible to provide a biaxially oriented polyester film that can reduce environmental impact, reduce yellowing, and suppress or reduce film breakage that may occur during stretching. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic cross-sectional view of the biaxially oriented polyester film in this embodiment. [Figure 2] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 3] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 4A] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 4B] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 5A] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 5B] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 6A] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 6B] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 7] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 8] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 9] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 10] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 11] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 12] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 13]This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 14] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 15A] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 15B] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 16] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 17A] This is a schematic cross-sectional view of a laminate in one embodiment. [Figure 17B] This is a schematic cross-sectional view of a laminate in one embodiment. [Modes for carrying out the invention]

[0041] <1. Introduction> Embodiments of the present invention will be described below. In the following, polyethylene terephthalate may be referred to as PET or pet. In other words, these terms will be used as synonyms. Machine Direction (hereinafter referred to as "MD") is sometimes called the longitudinal direction. In other words, MD and longitudinal direction are used as synonyms. Transverse Direction (hereinafter referred to as "TD") is sometimes referred to as the width direction. In other words, TD and width direction are used as synonyms. When describing embodiments of the present invention, expressions such as "the first layer 81, the second layer 82, and the third layer 83 are arranged in this order in the thickness direction of the biaxially oriented polyester film 8" may be used. This expression allows for the existence of other layers between the first layer 81 and the second layer 82, or between the second layer 82 and the third layer 83. The same applies to other expressions (i.e., similar expressions) that include the statement that multiple layers are "arranged in this order".

[0042] <2. Biaxially oriented polyester film> As shown in Figure 1, the biaxially oriented polyester film 8 of this embodiment is in the form of a film.

[0043] The biaxially oriented polyester film 8 contains chemically recycled polyester. Therefore, it can reduce the environmental impact.

[0044] Chemically recycled polyester is obtained by breaking down the polyester contained in used polyester products to the monomer level and then repolymerizing it. Because chemically recycled polyester is manufactured using polyester contained in used polyester products as raw material, it can reduce the environmental impact. Moreover, because foreign substances (such as catalysts, colorants, different plastics, and metals) are removed during the recycling process, chemically recycled polyester is more hygienic than mechanically recycled polyester.

[0045] Used polyester products can be cited as examples of polyester that can be broken down to the monomer level. Used polyester products may be in the form of bales, flakes, or pellets. Used PET bottles are preferred as examples of used polyester products.

[0046] One method for decomposing polyester to the monomer level is to crush and wash a PET bottle bale, then add at least ethylene glycol (EG) and a catalyst to it and heat it to decompose it to bis-2-hydroxyethyl terephthalate (BHET) (hereinafter sometimes referred to as the "BHET method") (see Patent Document 3, i.e., Japanese Patent Application Publication No. 2000-169623). Another method for decomposing polyester to the monomer level is, for example, the method described in Patent Document 4 (Japanese Patent Application Publication No. 2000-302707). Of course, polyester may be decomposed to the monomer level by methods other than those exemplified herein.

[0047] This section describes an example of the BHET method, specifically the procedure for obtaining BHET by decomposing polyethylene terephthalate, which makes up used PET bottles. The PET bottle bales are fed into a shredder and subjected to wet shredding. Wet shredding allows the PET bottle bales to be shredded in washing water (for example, tap water or groundwater to which detergent may be added as needed). The washing water may be at room temperature or it may be heated. The washing water is discharged from the crusher along with the PET bottle flakes, and foreign matter (such as metal, stone, glass, and sand) is removed by specific gravity separation. Next, rinse the flakes with deionized water and perform centrifugal dehydration if necessary. The flakes are melted, and then a catalyst and excess ethylene glycol are added and heated (i.e., depolymerization is performed). This allows the polyethylene terephthalate constituting the flakes to be depolymerized, resulting in a depolymerized solution in which BHET is dissolved in ethylene glycol. It is preferable to melt the flakes while they are still containing moisture (for example, while still containing moisture after centrifugal dehydration). This process removes foreign matter (such as different plastics, metals, or glass) that floats or precipitates in the depolymerization solution. Furthermore, since the melting point of cyclic oligomers in the depolymerization solution is higher than that of polyethylene terephthalate, low molecular weight components such as cyclic oligomers can also be removed by filtration. The depolymerization solution is passed through activated carbon (i.e., through a liquid), and then through an ion exchange resin. By passing the depolymerization solution through activated carbon, coloring components (for example, pigments, dyes, and compounds produced by the thermal degradation of organic matter) can be removed. By passing the depolymerization solution through an ion exchange resin, catalysts (for example, polymerization catalysts, depolymerization catalysts) and metal ions can be removed. Next, the depolymerization solution is cooled to precipitate BHET, and then the BHET and ethylene glycol are separated into solid and liquid phases. Vacuum evaporation is performed to remove the ethylene glycol remaining in BHET (i.e., to concentrate BHET). Molecular distillation is performed on the concentrated BHET. High-purity BHET can be obtained using this procedure. Although the procedure described here involves solid-liquid separation of BHET and ethylene glycol followed by vacuum evaporation, the ethylene glycol may be distilled off from the depolymerization solution instead.

[0048] Examples of chemically recycled polyesters include chemically recycled polyethylene terephthalate (hereinafter sometimes referred to as "chemically recycled PET"), chemically recycled polybutylene terephthalate, and chemically recycled polyethylene-2,6-naphthalate. Of course, these may also contain copolymer components. Chemically recycled PET is preferred because it is readily available and has excellent mechanical properties and heat resistance. These materials may be used individually or in combination of two or more types.

[0049] Chemically recycled polyester may contain copolymers of other components. Examples of dicarboxylic acid components as copolymers include isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid, and their ester-forming derivatives. On the other hand, examples of diol components as copolymers include diethylene glycol, hexamethylene glycol, neopentyl glycol, and cyclohexanedimethanol. Similarly, polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol can also be used. These may be used individually or in combination of two or more. Considering that PET, which constitutes PET bottles, generally contains copolymers of isophthalic acid to improve moldability into bottles, it is preferable that chemically recycled PET contains at least an isophthalic acid component as a copolymer.

[0050] When the total number of moles of dicarboxylic acid components in chemically recycled polyester is taken as 100 mol%, the number of moles of copolymer components is preferably 10 mol% or less, more preferably 8 mol% or less, even more preferably 5 mol% or less, and still more preferably 3 mol% or less. The number of moles of copolymer components is preferably 0.1 mol% or more, more preferably 1 mol% or more, and even more preferably 2 mol% or more. Chemically recycled polyester may contain one or more copolymer components that satisfy these preferred number of moles.

[0051] When the chemically recycled polyester is chemically recycled PET, if the total number of moles of dicarboxylic acid components in the chemically recycled PET is set to 100 mol%, the number of moles of isophthalic acid components is preferably 10 mol% or less, more preferably 8 mol% or less, even more preferably 5 mol% or less, and still more preferably 3 mol% or less. The number of moles of isophthalic acid components is preferably 0.1 mol% or more, more preferably 1 mol% or more, and even more preferably 2 mol% or more. The chemically recycled PET may contain one or more types of isophthalic acid components that satisfy these preferred number of moles.

[0052] The intrinsic viscosity of the chemically recycled polyester is preferably 0.50 dl / g or higher, more preferably 0.55 dl / g or higher, and even more preferably 0.57 dl / g or higher. When it is 0.50 dl / g or higher, the amount of low molecular weight components in the chemically recycled polyester can be limited to a certain extent, so the yellowish tint that the biaxially oriented polyester film 8 may exhibit can be further reduced. On the other hand, the intrinsic viscosity of the chemically recycled polyester is preferably 0.90 dl / g or lower, more preferably 0.85 dl / g or lower, even more preferably 0.80 dl / g or lower, even more preferably 0.75 dl / g or lower, and even more preferably 0.69 dl / g or lower. If the viscosity is 0.90 dl / g or less, the intrinsic viscosity of the biaxially oriented polyester film 8 can be limited to a certain extent, thereby further preventing excessive stress (i.e., tensile stress) during the stretching process in the manufacturing of the biaxially oriented polyester film 8. As a result, film breakage that may occur during stretching can be further suppressed or reduced. The chemically recycled polyester may contain one or more types that satisfy this suitable intrinsic viscosity.

[0053] In the molecular weight distribution curve obtained by gel permeation chromatography (GPC) of chemically recycled polyester, the area percentage of the region with a molecular weight of 1000 or less may be 3.5% or less, 3.0% or less, 2.5% or less, 2.2% or less, or 2.0% or less of the total peak area. On the other hand, this area percentage may be 0.8% or more, 1.0% or more, or 1.2% or more.

[0054] The melting resistivity at 285°C in chemically recycled polyester is, for example, 30.0 × 10⁻⁶. 8 It may be less than or equal to Ω·cm, and 25.0 × 10 8 It may be less than or equal to Ω·cm, and 20.0 × 10 8 It may be less than or equal to Ω·cm, and 15.0 × 10 8 It may be less than Ω·cm. The melting resistivity at 285°C in chemically recycled polyester is, for example, 0.5 × 10⁻⁶.8 It may be greater than or equal to Ω·cm, and 1.5 × 10 8 It may be greater than or equal to Ω·cm, and 3.0 × 10 8 It may be greater than or equal to Ω·cm, and 5.0 × 10 8 The resistivity may be Ω·cm or higher. Furthermore, the melting resistivity of chemically recycled polyester is preferably higher than that of fossil fuel-derived polyester or mechanically recycled polyester, as described later. The chemically recycled polyester may contain one or more types that satisfy such preferred melting resistivity.

[0055] Chemically recycled polyester may contain alkaline earth metal compounds, but it is preferable that it is substantially free of them. Since catalysts and metal ions are removed during the recycling process, chemically recycled polyester can be polymerized with catalysts other than alkaline earth metal compounds (for example, germanium-based catalysts or antimony-based catalysts) to be completely or almost free of alkaline earth metal compounds.

[0056] The content of alkaline earth metal compounds in chemically recycled polyester may be, for example, less than 30 ppm, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 0 ppm, based on alkaline earth metal atoms (i.e., in terms of alkaline earth metal atoms). Here, the content of alkaline earth metal compounds is the mass of alkaline earth metal compounds on an alkaline earth metal atom basis relative to the mass of chemically recycled polyester (i.e., the mass of alkaline earth metal compounds on an alkaline earth metal atom basis / the mass of chemically recycled polyester). Furthermore, the chemically recycled polyester may contain one or more alkaline earth metal compounds that satisfy the desired content requirements.

[0057] The magnesium compound content in the chemically recycled polyester may be, for example, less than 30 ppm, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 0 ppm, based on magnesium atoms (i.e., in terms of magnesium atoms). The chemically recycled polyester may contain one or more types of magnesium compounds that satisfy such a suitable magnesium compound content.

[0058] The phosphorus compound content in the chemically recycled polyester may be 10 ppm or more, 15 ppm or more, 20 ppm or more, or 30 ppm or more, based on phosphorus atoms (i.e., in terms of phosphorus atoms). On the other hand, the phosphorus compound content may be 300 ppm or less, 200 ppm or less, or 100 ppm or less, based on phosphorus atoms. Here, the phosphorus compound content is the mass of the phosphorus compound on a phosphorus atom basis relative to the mass of the chemically recycled polyester (i.e., the mass of the phosphorus compound on a phosphorus atom basis / the mass of the chemically recycled polyester). Furthermore, the chemically recycled polyester may contain one or more phosphorus compounds that meet the requirements for such a suitable phosphorus compound content.

[0059] The chemically recycled polyester content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the biaxially oriented polyester film 8 is considered to be 100% by mass. A content of 10% by mass or more further reduces the environmental burden. On the other hand, the chemically recycled polyester content is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the biaxially oriented polyester film 8 is considered to be 100% by mass.

[0060] The biaxially oriented polyester film 8 preferably contains fossil fuel-derived polyester, i.e., virgin polyester. Fossil fuel-derived polyester is a polyester obtained by condensation polymerization of a fossil fuel-derived diol compound and a fossil fuel-derived dicarboxylic acid compound. Fossil fuel-derived polyester generally offers a wider range of choices compared to chemically recycled polyester, and by using fossil fuel-derived polyester, the range of adjustability for the physical properties of the biaxially oriented polyester film 8 can be broadened.

[0061] Examples of fossil fuel-derived polyesters include fossil fuel-derived polyethylene terephthalate (hereinafter sometimes referred to as "fossil fuel-derived PET"), fossil fuel-derived polybutylene terephthalate, and fossil fuel-derived polyethylene-2,6-naphthalate. Of course, these may also contain copolymer components. Fossil fuel-derived PET is preferred because it can suppress costs and has excellent mechanical properties and heat resistance, and fossil fuel-derived homo-PET is more preferred. Homo-PET may also contain diethylene glycol, which is inevitably present. These may be used individually or in combination of two or more.

[0062] The intrinsic viscosity of the fossil fuel-derived polyester is preferably 0.50 dl / g or more, more preferably 0.55 dl / g or more, and even more preferably 0.57 dl / g or more. When it is 0.50 dl / g or more, the amount of low molecular weight components in the fossil fuel-derived polyester can be restricted to a certain extent, so that the yellowness that the biaxially oriented polyester film 8 can exhibit can be further reduced. On the other hand, the intrinsic viscosity of the fossil fuel-derived polyester is preferably 0.75 dl / g or less, more preferably 0.70 dl / g or less, even more preferably 0.68 dl / g or less, even more preferably 0.66 dl / g or less, and even more preferably 0.65 dl / g or less. When it is 0.75 dl / g or less, it is possible to further prevent the stress during stretching (i.e., stretching stress) in the process of manufacturing the biaxially oriented polyester film 8 from becoming excessively large. As a result, the breakage of the film that may occur during stretching can be further suppressed or reduced. Incidentally, the fossil fuel-derived polyester may contain one kind, or two or more kinds that satisfy such a suitable intrinsic viscosity.

[0063] In the molecular weight distribution curve obtained by gel permeation chromatography (GPC) of the fossil fuel-derived polyester, the area ratio of the region with a molecular weight of 1000 or less may be 3.5% or less, 3.0% or less, or 2.8% or less of the total peak area. On the other hand, this area ratio may be 1.0% or more, 1.5% or more, 1.8% or more, or 2.0% or more.

[0064] The melt specific resistance of the fossil fuel-derived polyester at 285 °C is, for example, 2.0×10 8 Ω·cm or less, 1.5×10 8 Ω·cm or less, 1.0×10 8 Ω·cm or less, 0.5×10 8 Ω·cm or less, 0.4×10 8 Ω·cm or less. The melt specific resistance of the fossil fuel-derived polyester at 285 °C is, for example, 0.05×10 8 Ω·cm or more, 0.1×10 8The resistivity may be Ω·cm or higher. Furthermore, the fossil fuel-derived polyester may contain one or more types that satisfy these suitable melting resistivity requirements.

[0065] The fossil fuel-derived polyester preferably contains an alkaline earth metal compound. The alkaline earth metal compound may be added to the fossil fuel-derived polyester, for example, as a polymerization catalyst for producing the fossil fuel-derived polyester, or it may be added to lower the melting resistivity of the biaxially oriented polyester film 8.

[0066] The content of alkaline earth metal compounds in fossil fuel-derived polyester is preferably 30 ppm or more, 35 ppm or more, 40 ppm or more, and 45 ppm or more, based on alkaline earth metal atoms (i.e., in terms of alkaline earth metal atoms). Here, the alkaline earth metal compound content is the mass of alkaline earth metal compounds on an alkaline earth metal atom basis relative to the mass of fossil fuel-derived polyester (i.e., the mass of alkaline earth metal compounds on an alkaline earth metal atom basis / the mass of fossil fuel-derived polyester). Furthermore, fossil fuel-derived polyester may contain one or more alkaline earth metal compounds that satisfy the desired content requirements.

[0067] The magnesium compound content in fossil fuel-derived polyester is preferably 30 ppm or more, 35 ppm or more, 40 ppm or more, and 45 ppm or more, based on magnesium atoms (i.e., in terms of magnesium atoms). The fossil fuel-derived polyester may contain one or more types of magnesium compounds that satisfy these preferred magnesium compound content requirements.

[0068] The phosphorus compound content in fossil fuel-derived polyester may be 10 ppm or more, 15 ppm or more, 20 ppm or more, or 30 ppm or more, based on phosphorus atoms (i.e., in terms of phosphorus atoms). On the other hand, the phosphorus compound content may be 300 ppm or less, 200 ppm or less, or 100 ppm or less, based on phosphorus atoms. Here, the phosphorus compound content is the mass of phosphorus compounds on a phosphorus atom basis relative to the mass of fossil fuel-derived polyester (i.e., the mass of phosphorus compounds on a phosphorus atom basis / the mass of fossil fuel-derived polyester). Furthermore, fossil fuel-derived polyester may contain one or more phosphorus compounds that satisfy the desired phosphorus compound content.

[0069] The content of fossil fuel-derived polyester is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the biaxially oriented polyester film 8 is considered to be 100% by mass. When it is 5% by mass or more, the range in which the physical properties of the biaxially oriented polyester film 8 can be adjusted can be further broadened. On the other hand, the content of fossil fuel-derived polyester is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the biaxially oriented polyester film 8 is considered to be 100% by mass.

[0070] The biaxially oriented polyester film 8 may or may not contain mechanically recycled polyester. Mechanically recycled polyester is polyester obtained from used polyester products without the process of breaking down the polyester contained in the used polyester product to the monomer level. Mechanically recycled polyester can be obtained, for example, by crushing and washing used polyester products and regenerating them into flakes or pellets as needed.

[0071] In the molecular weight distribution curve obtained by gel permeation chromatography (GPC) of mechanically recycled polyester, the area percentage of the region with a molecular weight of 1000 or less may be 4.5% or less of the total peak area, or 4.0% or less. On the other hand, this area percentage may be 2.5% or more, 3.0% or more, or 3.2% or more.

[0072] The biaxially oriented polyester film 8 preferably contains substantially no mechanically recycled polyester. The mechanically recycled polyester content is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.1% by mass or less, when the biaxially oriented polyester film 8 is considered as 100% by mass. It is preferable that the biaxially oriented polyester film 8 contains no mechanically recycled polyester at all.

[0073] The biaxially oriented polyester film 8 may also contain biomass polyester.

[0074] When the biaxially oriented polyester film 8 is considered to be 100% by mass, the polyester content (i.e., the polyester content including chemically recycled polyester) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0075] The biaxially oriented polyester film 8 may contain resins other than polyester (for example, chemically recycled polyester, fossil fuel-derived polyester).

[0076] The biaxially oriented polyester film 8 preferably further contains particles. Here, "the biaxially oriented polyester film 8 contains particles" means that if the biaxially oriented polyester film 8 contains multiple layers, at least one of the multiple layers contains particles.

[0077] Examples of particles include inorganic particles and organic particles. Examples of inorganic particles include silica (silicon oxide) particles, alumina (aluminum oxide) particles, titanium dioxide particles, calcium carbonate particles, kaolin particles, crystalline glass fillers, kaolin particles, talc particles, silica-alumina composite oxide particles, and barium sulfate particles. Among these, silica particles, calcium carbonate particles, and alumina particles are preferred, and silica particles and calcium carbonate particles are more preferred. Silica particles are particularly preferred because they can reduce haze. On the other hand, examples of organic particles include acrylic resin particles, melamine resin particles, silicone resin particles, and crosslinked polystyrene particles. Among these, acrylic resin particles are preferred. Examples of acrylic resin particles include particles made of polymethacrylate, polymethyl acrylate, or derivatives thereof. These may be used individually or in combination of two or more types.

[0078] The weight-average particle size of the particles is preferably 0.5 μm or larger, more preferably 0.8 μm or larger, and even more preferably 1.5 μm or larger. When it is 0.5 μm or larger, it is possible to form irregularities on the surface of the biaxially oriented polyester film 8. Therefore, slipperiness can be imparted to the biaxially oriented polyester film 8. In addition, when winding the biaxially oriented polyester film 8 into a roll, air that may be trapped can escape more easily, reducing the occurrence of appearance defects such as wrinkles and bubbles. On the other hand, the weight-average particle size of the particles is preferably 4.0 μm or smaller, more preferably 3.8 μm or smaller, and even more preferably 3.0 μm or smaller. When it is 4.0 μm or smaller, it is possible to prevent the formation of coarse protrusions on the biaxially oriented polyester film 8.

[0079] The particle content in the biaxially oriented polyester film 8 is preferably 100 ppm or more. A particle content of 100 ppm or more further enhances the slipperiness of the biaxially oriented polyester film 8 and further reduces the occurrence of appearance defects. On the other hand, the particle content in the biaxially oriented polyester film 8 is preferably 1000 ppm or less, and more preferably 800 ppm or less. A particle content of 1000 ppm or less prevents the arithmetic mean height Sa and maximum protrusion height Sp of the surface of the biaxially oriented polyester film 8 from becoming excessively high. In addition, it reduces the voids that may occur in the biaxially oriented polyester film 8, thereby suppressing the deterioration of transparency due to voids. Here, the particle content is the mass of the particles relative to the mass of the biaxially oriented polyester film 8 (i.e., the mass of the particles / the mass of the biaxially oriented polyester film 8).

[0080] The biaxially oriented polyester film 8 may further contain additives such as antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, plasticizers, and pigments.

[0081] In the molecular weight distribution curve obtained by gel permeation chromatography (GPC) of the biaxially oriented polyester film 8, the area percentage of the region with a molecular weight of 1000 or less is 5.5% or less of the total peak area. By keeping it at 5.5% or less, that is, by setting an upper limit on the content of components with a molecular weight of 1000 or less (i.e., low molecular weight components), the yellowish tint that the biaxially oriented polyester film 8 may exhibit can be reduced. By keeping this area ratio below 5.5%, when a sealant layer is formed on the biaxially oriented polyester film 8, the peel strength between the biaxially oriented polyester film 8 and the sealant layer can also be improved. This is thought to be because it suppresses the decrease in peel strength caused by low molecular weight components that can act as plastic components. This area percentage may be 5.4% or less, 5.3% or less, 5.2% or less, 5.1% or less, or 5.0% or less.

[0082] In addition, the area proportion of the region with a molecular weight of 1000 or less is 1.9% or more of the total peak area. By setting a minimum content of 1.9%, that is, by establishing a lower limit for the content of low molecular weight components, it is possible to ensure a sufficient amount of low molecular weight components that can function like plasticizers. By having a concentration of 1.9% or more, it is possible to limit the molecular weight of the polyester contained in the biaxially oriented polyester film 8 to a certain extent. This will be explained. Since low molecular weight components are incorporated into the polyester during the polymerization process, the higher the molecular weight of the polyester, the fewer low molecular weight components tend to be, and the lower the molecular weight of the polyester, the more low molecular weight components tend to be. According to this embodiment, since the area ratio of the region with a molecular weight of 1000 or less is 1.9% or more, that is, since a certain amount or more of low molecular weight components are present, it is possible to limit the molecular weight of the polyester contained in the biaxially oriented polyester film 8 to a certain extent. Therefore, it is possible to prevent the stress during stretching (i.e., tensile stress) in the manufacturing process of the biaxially oriented polyester film 8 from becoming excessively large, and as a result, it is possible to suppress or reduce the film breakage that may occur during stretching. This area percentage may be 2.0% or more, 2.2% or more, 2.4% or more, 2.6% or more, 2.8% or more, or 3.0% or more.

[0083] Color b per 1 μm thickness of biaxially oriented polyester film 8 *A value of 0.067 or less is preferred, 0.060 or less is more preferred, and 0.050 or less is even more preferred. A value of 0.067 or less can limit the yellowish tint that the biaxially oriented polyester film 8 may exhibit. Therefore, for example, when a printed layer is formed on the biaxially oriented polyester film 8, the influence of the color of the biaxially oriented polyester film 8 on the appearance (i.e., appearance) of the printed layer can be reduced. Also, for example, when a packaging container is made using the biaxially oriented polyester film 8, the influence of the color of the biaxially oriented polyester film 8 on the appearance of the contents can be reduced.

[0084] The intrinsic viscosity of the biaxially oriented polyester film 8 is preferably 0.50 dl / g or higher, and more preferably 0.51 dl / g or higher. A viscosity of 0.50 dl / g or higher improves mechanical properties, specifically tensile strength and puncture strength. On the other hand, the intrinsic viscosity of the biaxially oriented polyester film 8 is preferably 0.70 dl / g or lower, and more preferably 0.65 dl / g or lower. A viscosity of 0.70 dl / g or lower further prevents excessive stress (i.e., tensile stress) during the stretching process in the manufacturing of the biaxially oriented polyester film 8, and as a result, film breakage that may occur during stretching can be further suppressed or reduced.

[0085] The surface crystallinity of at least one side of the biaxially oriented polyester film 8 is preferably 1.10 or higher, more preferably 1.15 or higher, even more preferably 1.20 or higher, and even more preferably 1.25 or higher. Since the crystallization rate increases with decreasing polyester molecular weight, the surface crystallinity of the biaxially oriented polyester film 8 increases as the molecular weight of the polyester contained in the biaxially oriented polyester film 8 decreases. If the surface crystallinity is 1.10 or higher, it is possible to further restrict the molecular weight of the polyester contained in the biaxially oriented polyester film 8 to a certain level or lower, and to further restrict the amount of low molecular weight components that can act like plasticizers to a certain level or higher. Therefore, it is possible to further prevent the stress during stretching (i.e., stretching stress) during the manufacturing process of the biaxially oriented polyester film 8 from becoming excessively large, and as a result, it is possible to further suppress or reduce film breakage that may occur during stretching.

[0086] Similarly, the surface crystallinity of both sides of the biaxially oriented polyester film 8 is preferably 1.10 or higher, more preferably 1.15 or higher, even more preferably 1.20 or higher, and even more preferably 1.25 or higher.

[0087] The surface crystallinity of at least one face of the biaxially oriented polyester film 8 is preferably 1.35 or less, more preferably 1.34 or less, even more preferably 1.33 or less, even more preferably 1.32 or less, even more preferably 1.31 or less, even more preferably 1.30 or less, even more preferably 1.29 or less, and even more preferably 1.28 or less. A surface crystallinity of 1.35 or less prevents the biaxially oriented polyester film 8 from becoming excessively brittle (i.e., excessively poor toughness), thereby improving its mechanical properties, specifically tensile strength and puncture strength.

[0088] Similarly, the surface crystallinity of both sides of the biaxially oriented polyester film 8 is preferably 1.35 or less, more preferably 1.34 or less, even more preferably 1.33 or less, even more preferably 1.32 or less, even more preferably 1.31 or less, even more preferably 1.30 or less, even more preferably 1.29 or less, and even more preferably 1.28 or less.

[0089] The surface crystallinity is determined by ATR-IR. Specifically, it is determined by obtaining a spectrum using the total reflection decay method with a Fourier transform infrared spectrophotometer. The surface crystallinity is 1340 cm⁻¹. -1 Absorption appearing in the vicinity, and 1410cm -1The intensity ratio of absorption appearing in the vicinity, specifically, 1340 cm. -1 Strength / 1410cm -1 This is the strength. 1340cm -1 The absorption observed in the vicinity is due to the bending vibration of the CH2 (trans structure) of ethylene glycol. Meanwhile, at 1410 cm² -1 The absorption observed in the vicinity is unrelated to the crystal structure or orientation. ATR-IR measurements are performed under the following conditions. FT-IR: Bio Rad, DIGILAB FTS-60A / 896 Single-reflection ATR attachment: golden gate MKII (SPECAC made) Internal reflective element: Diamond Incident angle: 45° Resolution: 4cm -1 Total number of times: 128

[0090] The higher the melting point of the biaxially oriented polyester film 8, the better its heat resistance. Therefore, the melting point of the biaxially oriented polyester film 8 is preferably 251°C or higher, and more preferably 252°C or higher. On the other hand, the melting point of the biaxially oriented polyester film 8 is preferably 270°C or lower, and more preferably 268°C or lower. A melting point of 270°C or lower prevents the viscosity from becoming excessively high when melt-extruding the raw material polyester (e.g., chemically recycled polyester) for forming the biaxially oriented polyester film 8, resulting in high-speed film formation.

[0091] The melting resistivity at 285°C in the biaxially oriented polyester film 8 is 1.0 × 10⁻⁶. 8 Preferably less than Ω·cm, and 0.5 × 10 8 Ω·cm or less is more preferable, and 0.25 × 10 8 A value of Ω·cm or less is even more preferable. 1.0 × 10 8If the resistivity is Ω·cm or less, it is possible to effectively charge the surface of the polyester composition with static electricity when the film-like polyester composition, which is melt-extruded during the manufacturing process of the biaxially oriented polyester film 8, is adhered to the cooling drum by the electrostatic adhesion casting method, thereby enabling good adhesion of the polyester composition to the cooling drum. Therefore, it is possible to suppress the occurrence of pinner bubbles (i.e., streak-like defects caused by air entering between the polyester composition and the cooling drum) without excessively reducing the film formation speed. The film formation speed is the running speed (m / min) of the biaxially oriented polyester film 8 when it is wound onto the master roll. The film formation speed can be calculated by multiplying the casting speed by the MD stretching ratio. On the other hand, the melt resistivity is, for example, 0.01 × 10⁻⁶ 8 It may be greater than or equal to Ω·cm, and 0.03 × 10 8 It may be greater than or equal to Ω·cm, and 0.05 × 10 8 It may be greater than Ω·cm. 0.01 × 10 8 When the resistance is Ω·cm or higher, the formation of foreign matter (for example, foreign matter caused by alkaline earth metal compounds that can lower the resistivity of fusion) can be suppressed or reduced.

[0092] The melt resistivity of the biaxially oriented polyester film 8 can be adjusted by the content of alkaline earth metal compounds and phosphorus compounds in the biaxially oriented polyester film 8. For example, alkaline earth metal atoms (hereinafter sometimes referred to as "M2") that constitute the alkaline earth metal compound have the effect of lowering the melt resistivity, so the melt resistivity can be lowered by increasing the content of the alkaline earth metal compound. On the other hand, although phosphorus compounds themselves are not thought to have the effect of lowering the melt resistivity of the biaxially oriented polyester film 8, they contribute to the decrease in melt resistivity in the presence of alkaline earth metal compounds. The reason for this is not clear, but it is thought that by including phosphorus compounds, the generation of foreign matter can be suppressed and the amount of charge carriers can be increased.

[0093] Examples of alkaline earth metal compounds include hydroxides of alkaline earth metals, aliphatic dicarboxylates (acetates, butyrates, etc., preferably acetates), aromatic subcarboxylates, and salts with compounds having phenolic hydroxyl groups (salts with phenols, etc.). Examples of alkaline earth metals include magnesium, calcium, strontium, and barium. Magnesium is preferred among these. More specifically, magnesium hydroxide, magnesium acetate, calcium acetate, strontium acetate, and barium acetate can be mentioned. Magnesium acetate is preferred among these. Alkaline earth metal compounds can be used alone or in combination of two or more. Although there are definitions of alkaline earth metals that do not include magnesium, in this specification, alkaline earth metals are used as a term that includes magnesium. In other words, in this specification, alkaline earth metals refer to elements of Group IIa of the periodic table.

[0094] Furthermore, since chemically recycled polyester has catalysts and metal ions removed during the recycling process, it contains virtually no alkaline earth metal compounds. Therefore, the content of alkaline earth metal compounds can be adjusted by using chemically recycled polyester in combination with other polyesters (for example, fossil fuel-derived polyester or a masterbatch to which alkaline earth metal compounds have been added).

[0095] The content of alkaline earth metal compounds in the biaxially oriented polyester film 8 is preferably 20 ppm or more, more preferably 22 ppm or more, and even more preferably 24 ppm or more, based on alkaline earth metal atoms (i.e., in terms of alkaline earth metal atoms). On the other hand, the content of alkaline earth metal compounds is preferably 400 ppm or less, more preferably 350 ppm or less, and even more preferably 300 ppm or less, based on alkaline earth metal atoms. When it is 400 ppm or less, the generation of foreign matter and discoloration caused by alkaline earth metal compounds can be suppressed. Here, the content of the alkaline earth metal compound is the mass of the alkaline earth metal compound on a basis of alkaline earth metal atoms relative to the mass of the biaxially oriented polyester film 8 (i.e., the mass of the alkaline earth metal compound on a basis of alkaline earth metal atoms / the mass of the biaxially oriented polyester film 8).

[0096] The magnesium compound content in the biaxially oriented polyester film 8 is preferably 20 ppm or more, more preferably 22 ppm or more, and even more preferably 24 ppm or more, based on magnesium atoms (i.e., in terms of magnesium atoms). On the other hand, the magnesium compound content is preferably 400 ppm or less, more preferably 350 ppm or less, and even more preferably 300 ppm or less, based on magnesium atoms.

[0097] Examples of phosphorus compounds include phosphoric acids (phosphoric acid, phosphorous acid, hypophosphorous acid, etc.), their esters (alkyl esters, aryl esters, etc.), as well as alkylphosphonic acids, arylphosphonic acids, and their esters (alkyl esters, aryl esters, etc.). Preferred phosphorus compounds include phosphoric acid, aliphatic esters of phosphoric acid (alkyl esters of phosphoric acid, etc.; for example, mono-C1-6 alkyl esters of phosphoric acid such as monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, etc., di-C1-6 alkyl esters of phosphoric acid such as dimethyl phosphate, diethyl phosphate, dibutyl phosphate, etc., tri-C1-6 alkyl esters of phosphoric acid such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, etc.), aromatic esters of phosphoric acid (mono, di, or tri-C6-9 aryl esters of phosphoric acid such as triphenyl phosphate, tricresyl phosphate, etc.), and aliphatic esters of phosphorous acid (alkyl esters of phosphorous acid, etc.; for example, trimethyl phosphorous acid, tri-C1-6 alkyl esters of phosphorous acid, trimethyl phosphorous acid, tri-C1-6 alkyl esters of phosphorous acid, etc.). Examples of phosphorus compounds include mono, di, or tri C1-6 alkyl esters of phosphite such as tributyl phosphate, alkylphosphonic acids (C1-6 alkylphosphonic acids such as methylphosphonic acid and ethylphosphonic acid), alkyl esters of alkylphosphonic acids (mono or di C1-6 alkyl esters of C1-6 alkylphosphonic acids such as dimethyl methylphosphonic acid and dimethyl ethylphosphonic acid), alkyl esters of arylphosphonic acids (mono or di C1-6 alkyl esters of C6-9 arylphosphonic acids such as dimethyl phenylphosphonic acid and diethyl phenylphosphonic acid), and aryl esters of arylphosphonic acids (mono or di C6-9 aryl esters of C6-9 arylphosphonic acids such as diphenyl phenylphosphonic acid). Particularly preferred phosphorus compounds include phosphoric acid and trialkyl phosphates (such as trimethyl phosphate). These phosphorus compounds can be used alone or in combination of two or more.

[0098] The phosphorus compound content in the biaxially oriented polyester film 8 is preferably 10 ppm or more, more preferably 11 ppm or more, and even more preferably 12 ppm or more, based on phosphorus atoms (i.e., in terms of phosphorus atoms). A content of 10 ppm or more effectively reduces the melting resistivity and suppresses the formation of foreign matter. The phosphorus compound content may be 20 ppm or more, 40 ppm or more, or 50 ppm or more, based on phosphorus atoms. On the other hand, the phosphorus compound content is preferably 600 ppm or less, more preferably 550 ppm or less, and even more preferably 500 ppm or less, based on phosphorus atoms. A content of 600 ppm or less reduces the formation of diethylene glycol. The phosphorus compound content may be 400 ppm or less, 200 ppm or less, or 100 ppm or less, based on phosphorus atoms. Here, the phosphorus compound content is the mass of the phosphorus compound on a phosphorus atom basis relative to the mass of the biaxially oriented polyester film 8 (i.e., the mass of the phosphorus compound on a phosphorus atom basis / the mass of the biaxially oriented polyester film 8).

[0099] In the biaxially oriented polyester film 8, the mass ratio of alkaline earth metal atoms (i.e., M2) to phosphorus atoms (P), i.e., the ratio of the mass of M2 to the mass of P (M2 mass / P mass), is preferably 1.0 or higher, more preferably 1.1 or higher, even more preferably 1.2 or higher, even more preferably 1.3 or higher, and even more preferably 1.4 or higher. A ratio of 1.0 or higher effectively reduces the melting resistivity of the biaxially oriented polyester film 8. On the other hand, this mass ratio is preferably 5.0 or lower, more preferably 4.5 or lower, and even more preferably 4.0 or lower. A ratio of 5.0 or lower suppresses the generation of foreign matter and discoloration.

[0100] When the total number of moles of dicarboxylic acid components in the biaxially oriented polyester film 8 is set to 100 mol%, the number of moles of isophthalic acid components is preferably 0.01 mol% or more, more preferably 0.05 mol% or more, even more preferably 0.10 mol% or more, even more preferably 0.15 mol% or more, even more preferably 0.20 mol% or more, and even more preferably 0.40 mol% or more. If it is 0.01 mol% or more, the lamination strength of the biaxially oriented polyester film 8 can be improved. On the other hand, the number of moles of isophthalic acid components is preferably 3.0 mol% or less, more preferably 2.5 mol% or less, even more preferably 2.2 mol% or less, and even more preferably 2.0 mol% or less. If it is 3.0 mol% or less, it is possible to prevent an excessive decrease in crystallinity, and therefore an excessive decrease in mechanical properties can be prevented. In addition, it is possible to reduce the thickness unevenness of the biaxially oriented polyester film 8 and to limit the heat shrinkage rate of the biaxially oriented polyester film 8.

[0101] The tensile strength of the biaxially oriented polyester film 8 in at least one direction is preferably 180 MPa or higher, more preferably 185 MPa or higher, and even more preferably 190 MPa or higher. When the tensile strength is 180 MPa or higher, products with excellent strength (e.g., packaging containers) can be manufactured using the biaxially oriented polyester film 8.

[0102] Similarly, the tensile strength of the biaxially oriented polyester film 8 in the MD (i.e., 0° direction), 45° direction, TD (i.e., 90° direction), and 135° direction is preferably 180 MPa or higher, more preferably 185 MPa or higher, and even more preferably 190 MPa or higher.

[0103] The tensile strength of the biaxially oriented polyester film 8 in at least one direction is preferably 350 MPa or less, more preferably 340 MPa or less, and even more preferably 330 MPa or less. A tensile strength of 350 MPa or less further prevents excessive stress (i.e., tensile stress) during stretching in the manufacturing process of the biaxially oriented polyester film 8, thereby further suppressing or reducing film breakage that may occur during stretching. The tensile strength may also be 320 MPa or less.

[0104] Similarly, the tensile strength of the biaxially oriented polyester film 8 in the MD (i.e., 0° direction), 45° direction, TD (i.e., 90° direction), and 135° direction is preferably 350 MPa or less, more preferably 340 MPa or less, and even more preferably 330 MPa or less. The tensile strength may also be 320 MPa or less.

[0105] The puncture strength of the biaxially oriented polyester film 8 is preferably 0.50 N / μm or higher, more preferably 0.52 N / μm or higher, and even more preferably 0.55 N / μm or higher. When the puncture strength is 0.50 N / μm or higher, products with excellent strength (e.g., packaging containers) can be manufactured using the biaxially oriented polyester film 8. For example, packaging containers that are resistant to punctures can be manufactured using the biaxially oriented polyester film 8.

[0106] The lamination strength of the biaxially oriented polyester film 8 is preferably 3.0 N / 15 mm or higher, more preferably 3.5 N / 15 mm or higher, and even more preferably 4.0 N / 15 mm or higher. When the lamination strength is 3.0 N / 15 mm or higher, a product (e.g., a packaging container) can be made that is less likely to peel off between the biaxially oriented polyester film 8 and the sealant layer when the sealant layer is provided on the biaxially oriented polyester film 8.

[0107] The thermal shrinkage rate in the longitudinal direction, i.e., the median diameter (MD), of the biaxially oriented polyester film 8 is preferably 2.0% or less, and more preferably 1.8% or less. A rate of 2.0% or less reduces the frequency of thermal deformation and wrinkles when the biaxially oriented polyester film 8 undergoes secondary processing such as vapor deposition or printing. The thermal shrinkage rate of the MD may be, for example, 0.5% or more, or 0.8% or more.

[0108] The thermal shrinkage rate in the width direction, i.e., TD, of the biaxially oriented polyester film 8 is preferably -1.0% to 1.0%, and more preferably -0.8% to 0.8%. When it is -1.0% to 1.0%, the frequency of deformation and wrinkles caused by heat can be reduced when secondary processing such as vapor deposition or printing is performed.

[0109] The thickness of the biaxially oriented polyester film 8 is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 9 μm or more. A thickness of 5 μm or more provides excellent rigidity, thereby reducing the frequency of wrinkles when winding the biaxially oriented polyester film 8. On the other hand, the thickness of the biaxially oriented polyester film 8 is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 25 μm or less. The thinner the film, the lower the cost.

[0110] The biaxially oriented polyester film 8 includes a first layer 81 (hereinafter also referred to as the "surface layer 81"), a second layer 82 (hereinafter also referred to as the "core layer 82"), and a third layer 83 (hereinafter also referred to as the "surface layer 83"). The first layer 81, the second layer 82, and the third layer 83 are arranged in this order in the thickness direction of the biaxially oriented polyester film 8. Other layers may exist between the first layer 81 and the second layer 82, or between the second layer 82 and the third layer 83.

[0111] The first layer 81, i.e., the surface layer 81, preferably contains chemically recycled polyester. Including chemically recycled polyester in the first layer 81 further reduces the environmental burden.

[0112] The explanation of chemically recycled polyester in the first layer 81 is omitted because it overlaps with the explanation above (i.e., the explanation of chemically recycled polyester in the biaxially oriented polyester film 8). Therefore, the explanation of chemically recycled polyester in the biaxially oriented polyester film 8 can also be treated as the explanation of chemically recycled polyester in the first layer 81.

[0113] The chemically recycled polyester content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the first layer 81 is considered to be 100% by mass. A content of 10% by mass or more further reduces the environmental burden. On the other hand, the chemically recycled polyester content is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the first layer 81 is considered to be 100% by mass.

[0114] The first layer 81 preferably contains fossil fuel-derived polyester. The explanation of the fossil fuel-derived polyester in the first layer 81 is omitted because it overlaps with the explanation above (i.e., the explanation of the fossil fuel-derived polyester in the biaxially oriented polyester film 8). Therefore, the explanation of the fossil fuel-derived polyester in the biaxially oriented polyester film 8 can also be treated as the explanation of the fossil fuel-derived polyester in the first layer 81.

[0115] The content of fossil fuel-derived polyester is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the first layer 81 is considered to be 100% by mass. A content of 5% by mass or more ensures a certain degree of flexibility in adjusting the physical properties of the first layer 81. On the other hand, the content of fossil fuel-derived polyester can be 100% by mass or less, when the first layer 81 is considered to be 100% by mass. The content of fossil fuel-derived polyester is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0116] The first layer 81 may also contain other polyesters, such as mechanically recycled polyester or biomass polyester.

[0117] When the first layer 81 is considered to be 100% by mass, the polyester content is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0118] The first layer 81 may contain resins other than polyester.

[0119] The first layer 81 preferably further contains particles. When the first layer 81 contains particles, it is possible to form irregularities on the surface of the biaxially oriented polyester film 8. Therefore, the biaxially oriented polyester film 8 can be given slipperiness. In addition, when the biaxially oriented polyester film 8 is wound into a roll, air that may get trapped can escape more easily, and the occurrence of appearance defects such as wrinkles and bubbles can be reduced.

[0120] The description of the particles in the first layer 81 is omitted because it overlaps with the description above (i.e., the description of the particles in the biaxially oriented polyester film 8). Therefore, the description of the particles in the biaxially oriented polyester film 8 can also be treated as the description of the particles in the first layer 81.

[0121] The particle content in the first layer 81 is preferably 500 ppm or more, more preferably 600 ppm or more, and even more preferably 700 ppm or more. A content of 500 ppm or more can further impart slipperiness to the biaxially oriented polyester film 8 and further reduce the occurrence of appearance defects. On the other hand, the particle content in the first layer 81 may be 3000 ppm or less, 2000 ppm or less, or 1500 ppm or less. Here, the particle content is the mass of the particles relative to the mass of the first layer 81 (i.e., the mass of the particles / the mass of the first layer 81).

[0122] The thickness of the first layer 81 is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. The thickness of the first layer 81 is preferably 7 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

[0123] The description of the third layer 83, or surface layer 83, is omitted because it overlaps with the description of the first layer 81. Therefore, the description of the first layer 81 can also be treated as a description of the third layer 83. For example, the descriptions of the first layer 81, such as chemically recycled polyester, fossil fuel-derived polyester, particles, and thickness, can be treated as a description of the third layer 83. Of course, the first layer 81 and the third layer 83 can be independent of each other in terms of composition and physical properties (for example, thickness). Therefore, for example, the compositions of the first layer 81 and the third layer 83 may be the same or different. The thicknesses of both may be the same or different.

[0124] The second layer 82, or the core layer 82, preferably contains chemically recycled polyester. Including chemically recycled polyester in the second layer 82 further reduces the environmental impact.

[0125] The explanation of chemically recycled polyester in the second layer 82 is omitted because it overlaps with the explanation above (i.e., the explanation of chemically recycled polyester in the biaxially oriented polyester film 8). Therefore, the explanation of chemically recycled polyester in the biaxially oriented polyester film 8 can also be treated as the explanation of chemically recycled polyester in the second layer 82.

[0126] The chemically recycled polyester content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the second layer 82 is considered to be 100% by mass. A content of 10% by mass or more further reduces the environmental burden. On the other hand, the chemically recycled polyester content is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the second layer 82 is considered to be 100% by mass.

[0127] The second layer 82 preferably contains fossil fuel-derived polyester. The explanation of fossil fuel-derived polyester in the second layer 82 is omitted because it overlaps with the explanation above (i.e., the explanation of fossil fuel-derived polyester in the biaxially oriented polyester film 8). Therefore, the explanation of fossil fuel-derived polyester in the biaxially oriented polyester film 8 can also be treated as the explanation of fossil fuel-derived polyester in the second layer 82.

[0128] The content of fossil fuel-derived polyester is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the second layer 82 is considered to be 100% by mass. A content of 5% by mass or more ensures a certain degree of flexibility in adjusting the physical properties of the second layer 82. On the other hand, the content of fossil fuel-derived polyester is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the first layer 81 is considered to be 100% by mass.

[0129] The second layer 82 may also contain other polyesters, such as mechanically recycled polyester or biomass polyester.

[0130] When the second layer 82 is considered to be 100% by mass, the polyester content is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0131] The second layer 82 may contain resins other than polyester.

[0132] The second layer 82 may or may not contain particles. The explanation of particles in the second layer 82 is omitted because it overlaps with the explanation above (i.e., the explanation of particles in the biaxially oriented polyester film 8). Therefore, the explanation of particles in the biaxially oriented polyester film 8 can also be treated as the explanation of particles in the second layer 82. If the second layer 82 does not contain particles, voids that may occur around the particles will not be generated, thus preventing odor components from passing through the biaxially oriented polyester film 8. In addition, it is cost-effective because it becomes easier to use recovered raw materials from the edge portions generated in the film-making process and recycled raw materials from other film-making processes in a timely manner.

[0133] The particle content in the second layer 82 may be 3000 ppm or less, 2000 ppm or less, 1500 ppm or less, 1000 ppm or less, 500 ppm or less, 100 ppm or less, 50 ppm or less, or 0 ppm or less. Here, the particle content is the mass of the particles relative to the mass of the second layer 82 (i.e., the mass of the particles / the mass of the second layer 82).

[0134] The thickness of the second layer 82 is preferably greater than the thickness of the first layer 81 or the third layer 83. The thickness of the second layer 82 is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 9 μm or more. When the thickness is 5 μm or more, the rigidity of the biaxially oriented polyester film 8 is excellent, which reduces the frequency of wrinkles when winding the biaxially oriented polyester film 8. On the other hand, the thickness of the biaxially oriented polyester film 8 is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. The thinner the film, the lower the cost.

[0135] Some supplementary explanations will be given regarding the composition patterns of the first layer 81, the second layer 82, and the third layer 83. One possible composition pattern (hereinafter also referred to as "composition pattern A") is one in which the first layer 81 contains chemically recycled polyester, the second layer 82 contains chemically recycled polyester, and the third layer 83 contains chemically recycled polyester. According to composition pattern A, chemically recycled polyester with few impurities constitutes both surface layers of the biaxially oriented polyester film 8, thus reducing defects in the biaxially oriented polyester film 8. The explanation of the first layer 81, the second layer 82, and the third layer 83 in composition pattern A is omitted as it overlaps with the explanation above (i.e., the explanation of the first layer 81, the second layer 82, and the third layer 83). Therefore, the explanation above can also be treated as an explanation of the first layer 81, the second layer 82, and the third layer 83 in composition pattern A. Thus, the first layer 81 may contain polyester other than chemically recycled polyester, the second layer 82 may contain polyester other than chemically recycled polyester, and the third layer 83 may contain polyester other than chemically recycled polyester. A second composition pattern (hereinafter also referred to as "composition pattern B") is one in which the first layer 81 contains chemically recycled polyester, while neither the second layer 82 nor the third layer 83 contains chemically recycled polyester. According to composition pattern B, chemically recycled polyester with fewer impurities constitutes the surface layer of the biaxially oriented polyester film 8, thus reducing defects in the biaxially oriented polyester film 8. The explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern B is omitted as it overlaps with the explanation above (i.e., the explanation of the first layer 81, second layer 82, and third layer 83). Therefore, the explanation above can also be treated as an explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern B. Thus, the first layer 81 may contain polyester other than chemically recycled polyester. Furthermore, in composition pattern B, it is preferable that the second layer 82 and / or the third layer 83 contain mechanically recycled polyester. This allows for an even higher proportion of recycled materials, thus further reducing the environmental burden. A third composition pattern (hereinafter also referred to as "composition pattern C") is one in which the second layer 82 contains chemically recycled polyester, while neither the first layer 81 nor the third layer 83 contains chemically recycled polyester. The explanations of the first layer 81, second layer 82, and third layer 83 in composition pattern C are omitted as they overlap with the explanations above (i.e., the explanations of the first layer 81, second layer 82, and third layer 83). Therefore, the explanations above can also be treated as explanations of the first layer 81, second layer 82, and third layer 83 in composition pattern C. Thus, the second layer 82 may contain polyester other than chemically recycled polyester. Furthermore, in composition pattern C, it is preferable that the first layer 81 and / or the third layer 83 contain mechanically recycled polyester. This allows for an even higher proportion of recycled materials, thus further reducing the environmental burden. A fourth composition pattern (hereinafter also referred to as "composition pattern D") is one in which the first layer 81 contains chemically recycled polyester, the second layer 82 contains chemically recycled polyester, and the third layer 83 does not contain chemically recycled polyester. According to composition pattern D, chemically recycled polyester with fewer impurities constitutes the surface layer of the biaxially oriented polyester film 8, thus reducing defects in the biaxially oriented polyester film 8. The explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern D is omitted as it overlaps with the explanation above (i.e., the explanation of the first layer 81, second layer 82, and third layer 83). Therefore, the explanation above can also be treated as the explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern D. Therefore, the first layer 81 may contain polyester other than chemically recycled polyester, and the second layer 82 may contain polyester other than chemically recycled polyester. Furthermore, in composition pattern D, it is preferable that the third layer 83 contains mechanically recycled polyester. This allows for an even higher proportion of recycled materials, thus further reducing the environmental burden. A fifth composition pattern (hereinafter also referred to as "composition pattern E") is one in which the first layer 81 contains chemically recycled polyester, the second layer 82 does not contain chemically recycled polyester, and the third layer 83 contains chemically recycled polyester. According to composition pattern E, chemically recycled polyester with few impurities constitutes both surface layers of the biaxially oriented polyester film 8, thus reducing defects in the biaxially oriented polyester film 8. The explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern E is omitted as it overlaps with the explanation above (i.e., the explanation of the first layer 81, second layer 82, and third layer 83). Therefore, the explanation above can also be treated as the explanation of the first layer 81, second layer 82, and third layer 83 in composition pattern E. Thus, the first layer 81 may contain polyester other than chemically recycled polyester, and the third layer 83 may contain polyester other than chemically recycled polyester. Furthermore, in composition pattern E, it is preferable that the second layer 82 contains mechanically recycled polyester. This allows for an even higher proportion of recycled materials, thus further reducing the environmental burden.

[0136] A biaxially oriented polyester film 8 can be produced by supplying raw materials for forming the first layer 81 to a first extruder, raw materials for forming the second layer 82 to a second extruder, and raw materials for forming the third layer 83 to a third extruder, then melting these materials, guiding them from the first, second, and third extruders to a T-die, laminating them in the T-die, extruding them from the T-die, solidifying them in a cooling drum, and then biaxially stretching them. Of course, these raw materials may also be guiding them from the first, second, and third extruders to a feed block, laminating them in the feed block, and then extruding them from the T-die. In addition, methods other than the T-die method, such as the tubular method, may also be used.

[0137] Examples of raw materials for forming the first layer 81 include chemically recycled polyester, fossil fuel-derived polyester, particle-containing masterbatches, and alkaline earth metal compound / phosphorus compound-containing masterbatches (hereinafter sometimes referred to as "MP masterbatches"). It is preferable to use at least these as raw materials for forming the first layer 81.

[0138] The particle-containing masterbatch may contain polyester and particles (e.g., silica). The particle-containing masterbatch may contain particles (e.g., silica) in the highest concentration among the individual raw materials for forming the first layer 81.

[0139] The polyester in the particle-containing masterbatch may be chemically recycled polyester, fossil fuel-derived polyester, mechanically recycled polyester, or biomass polyester. Among these, chemically recycled polyester and fossil fuel-derived polyester are preferred, and fossil fuel-derived polyester is more preferred.

[0140] The particle content in the particle-containing masterbatch is preferably 5,000 ppm or more, more preferably 10,000 ppm or more, and even more preferably 20,000 ppm or more. On the other hand, the particle content in the particle-containing masterbatch may be 1,000,000 ppm or less, 200,000 ppm or less, or 100,000 ppm or less. Here, the particle content is the mass of the particles relative to the mass of the particle-containing masterbatch (i.e., the mass of the particles / the mass of the particle-containing masterbatch).

[0141] On the other hand, the MP masterbatch (i.e., the alkaline earth metal compound / phosphorus compound-containing masterbatch) may contain polyester, alkaline earth metal compounds, and phosphorus compounds. The MP masterbatch contains the alkaline earth metal compound in the highest concentration among the individual raw materials for forming the first layer 81, and also contains the phosphorus compound in the highest concentration.

[0142] The polyester in the MP masterbatch may be chemically recycled polyester, fossil fuel-derived polyester, mechanically recycled polyester, or biomass polyester. Among these, chemically recycled polyester and fossil fuel-derived polyester are preferred, and fossil fuel-derived polyester is more preferred. The MP masterbatch can be produced, for example, by adding a large amount of alkaline earth metal compounds and phosphorus compounds when polymerizing the polyester.

[0143] The content of alkaline earth metal compounds in the MP masterbatch is preferably 200 ppm or more, 400 ppm or more, 600 ppm or more, and 700 ppm or more, based on alkaline earth metal atoms (i.e., in terms of alkaline earth metal atoms). The content of alkaline earth metal compounds may be 3000 ppm or less, 2000 ppm or less, or 1500 ppm or less, based on alkaline earth metal atoms. Here, the content of alkaline earth metal compounds is the mass of alkaline earth metal compounds on an alkaline earth metal atom basis relative to the mass of the MP masterbatch (i.e., the mass of alkaline earth metal compounds on an alkaline earth metal atom basis / the mass of the MP masterbatch).

[0144] The magnesium compound content in the MP masterbatch is preferably 200 ppm or more, 400 ppm or more, 600 ppm or more, and 700 ppm or more, based on the number of magnesium compound atoms (i.e., in terms of magnesium compound atoms). The alkaline earth metal compound content may be 3000 ppm or less, 2000 ppm or less, or 1500 ppm or less, based on the number of magnesium compound atoms.

[0145] The phosphorus compound content in the MP masterbatch is preferably 150 ppm or more, more preferably 300 ppm or more, even more preferably 350 ppm or more, and even more preferably 400 ppm or more, based on phosphorus atoms. On the other hand, the phosphorus compound content may be 1000 ppm or less, 800 ppm or less, or 700 ppm or less, based on phosphorus atoms. Here, the phosphorus compound content is the mass of the phosphorus compound on a phosphorus atom basis relative to the mass of the MP masterbatch (i.e., the mass of the phosphorus compound on a phosphorus atom basis / the mass of the MP masterbatch).

[0146] Alternatively, instead of the MP masterbatch, an alkaline earth metal compound-containing masterbatch and a phosphorus compound-containing masterbatch may be used. The alkaline earth metal compound-containing masterbatch may contain polyester and alkaline earth metal compounds. This masterbatch contains the alkaline earth metal compound at the highest concentration among the individual raw materials for forming the first layer 81. The phosphorus compound-containing masterbatch may contain polyester and phosphorus compounds. This masterbatch contains the phosphorus compound at the highest concentration among the individual raw materials for forming the first layer 81.

[0147] Examples of raw materials for forming the second layer 82 include chemically recycled polyester, fossil fuel-derived polyester, and alkaline earth metal compound / phosphorus compound-containing masterbatches (i.e., MP masterbatches). It is preferable to use at least these as raw materials for forming the second layer 82.

[0148] The explanation of the MP masterbatch in the second layer 82 is omitted because it overlaps with the explanation above (i.e., the explanation of the MP masterbatch in the first layer 81). Therefore, the explanation of the MP masterbatch in the first layer 81 can also be treated as the explanation of the MP masterbatch in the second layer 82.

[0149] The description of the raw materials for forming the third layer 83 is omitted because it overlaps with the description of the raw materials for forming the first layer 81. Therefore, the description of the raw materials for forming the first layer 81 can also be treated as a description of the raw materials for forming the third layer 83. Of course, the raw materials for forming the first layer 81 and the raw materials for forming the third layer 83 can be independent of each other. Therefore, for example, these raw materials may be the same or different.

[0150] These raw materials (specifically, the raw materials for forming the first layer 81, the second layer 82, and the third layer 83) are preferably dried before being supplied to the extruder. For drying, a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer can be used.

[0151] Raw materials for forming the first layer 81 are supplied to the first extruder, raw materials for forming the second layer 82 are supplied to the second extruder, and raw materials for forming the third layer 83 are supplied to the third extruder. After melting these materials, they are guided from the first, second, and third extruders to a T-die or feed block, where they can be laminated. It is preferable that these raw materials melt at a temperature above the melting point of the polyester in the raw materials, and between 200°C and 300°C.

[0152] A film-like polyester composition can be extruded from a T-die and cast into a cooling drum. This allows for rapid cooling and solidification of the polyester composition, resulting in a substantially unoriented, unstretched film. The surface temperature of the cooling drum is preferably 40°C or lower.

[0153] Next, the unstretched film can be biaxially stretched. Biaxial stretching can improve mechanical properties such as tensile strength. Biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. Sequential biaxial stretching is preferred. In sequential biaxial stretching, it is preferable to stretch the unstretched film in the longitudinal direction, i.e., MD, and then stretch the sheet after MD stretching in the width direction, i.e., TD. This makes it possible to produce a biaxially oriented polyester film 8 with excellent thickness uniformity at a relatively fast film formation rate.

[0154] The temperature at which the unstretched film is stretched in the longitudinal direction, i.e., the MD stretching temperature, is preferably between 80°C and 130°C. The stretching ratio at this time, i.e., the MD stretching ratio, is preferably between 3.3 times and 4.7 times. When the temperature is between 80°C and 4.7 times, the shrinkage stress in the longitudinal direction can be reduced, the bowing phenomenon can be reduced, and variations and distortions in molecular orientation and thermal shrinkage rate in the width direction of the biaxially oriented polyester film 8 can be reduced.

[0155] The method for stretching the unstretched film in the longitudinal direction may be, for example, a multi-stage stretching method between multiple rolls, or a method of stretching by heating with an infrared heater or the like. The latter is preferred because it is easier to raise the temperature, localized heating is easy, and scratches caused by the rolls can be reduced.

[0156] Surface treatments such as corona treatment or plasma treatment may be applied to at least one surface of the longitudinally stretched film, as needed. A resin dispersion or resin dissolving solution may be applied to at least one surface of the longitudinally stretched film, as needed. This can impart functions such as slipperiness, adhesion, and antistatic properties. Both surface treatments such as corona treatment or plasma treatment and the application of a resin dispersion or resin dissolving solution may be performed.

[0157] A film stretched in the longitudinal direction is guided to a tenter device, where both ends of the film are gripped with clips. After heating the film to a predetermined temperature with hot air, the film can be stretched in the width direction by increasing the distance between the clips while conveying it in the longitudinal direction.

[0158] The preheating temperature when stretching the film in the width direction is preferably between 100°C and 130°C. A temperature of 100°C or higher can reduce the shrinkage stress generated when stretching in the longitudinal direction, reduce the bowing phenomenon, and reduce variations and distortions in molecular orientation and thermal shrinkage rate in the width direction of the biaxially oriented polyester film 8.

[0159] The temperature at which the film is stretched in the width direction, i.e., the TD stretching temperature, is preferably between 105°C and 135°C. A temperature of 105°C or higher can reduce the longitudinal stretching stress caused by TD stretching, thereby suppressing the increase in bowing phenomena. A temperature of 135°C or lower can suppress or reduce film breakage that may occur during stretching, even when using polyester with a heating crystallization temperature of around 130°C (for example, chemically recycled polyester).

[0160] The stretching ratio, or TD stretching ratio, when stretching the film in the width direction is preferably between 3.5 and 5.0. A ratio of 3.5 or higher makes it easier to obtain a high yield in terms of material balance, suppresses a decrease in mechanical strength, and also suppresses an increase in thickness unevenness in the width direction. A ratio of 5.0 or lower can suppress or reduce film breakage that may occur during stretching.

[0161] The biaxially oriented film can be heated for heat setting. The heat setting temperature is preferably between 220°C and 250°C. Above 220°C, it is possible to prevent the thermal shrinkage rate from becoming excessively high in both the longitudinal and width directions. Therefore, the thermal dimensional stability during secondary processing can be improved. Below 250°C, it is possible to suppress the increase in bowing phenomena and reduce variations and distortions in molecular orientation and thermal shrinkage rate in the width direction of the biaxially oriented polyester film 8.

[0162] A thermal relaxation treatment can be performed in conjunction with or separately from the thermal setting treatment. A preferred thermal relaxation rate in the width direction is 4% to 8%. A rate of 4% or higher prevents excessive thermal shrinkage in the width direction, thereby improving thermal dimensional stability during secondary processing. A rate of 8% or lower prevents excessively high longitudinal tensile stress in the center of the film's width direction, thus suppressing an increase in bowing.

[0163] During the thermal relaxation process, while the biaxially stretched film shrinks due to thermal relaxation, the constraint force in the width direction decreases, causing the film to sag under its own weight, or the film may bulge due to the accompanying airflow of hot air blown from nozzles installed above and below the film. Because the film is prone to vertical movement in this way, the change in the orientation angle of the biaxially oriented polyester film 8 tends to fluctuate significantly. To ensure that the film remains parallel, for example, the airflow velocity of the hot air blown from the nozzles can be adjusted.

[0164] Corona discharge treatment, glow discharge treatment, flame treatment, and surface roughening treatment may be applied. Additionally, anchor coating treatment may be applied.

[0165] The wide, biaxially oriented polyester film 8, stretched and formed using this procedure, may be wound into a roll using a winder device. In other words, a master roll may be produced.

[0166] The width of the master roll is preferably between 5,000 mm and 10,000 mm. If it is 5,000 mm or wider, the cost per unit area of ​​the film can be reduced in subsequent secondary processing such as slitting, vapor deposition, and printing.

[0167] The master roll length is preferably between 10,000m and 100,000m. A length of 10,000m or more allows for reduced costs per unit area in subsequent secondary processing such as slitting, vapor deposition, and printing.

[0168] The master roll may be slit and then wound up to form a roll. In other words, a film roll may be manufactured.

[0169] The film roll width is preferably between 400mm and 3000mm. A width of 400mm or more reduces the frequency of film roll changes during the printing process, thus lowering costs. A width of 3000mm or less prevents the roll from becoming excessively large and thus excessively heavy, resulting in good handling.

[0170] The film roll length is preferably between 2,000m and 65,000m. A length of 2,000m or more reduces the frequency of film roll changes during the printing process, thus lowering costs. A length of 65,000m or less prevents the roll diameter from becoming excessively large and the roll weight from becoming excessively heavy, resulting in good handling.

[0171] The core used for film rolls is not particularly limited; for example, cylindrical cores made of plastic, metal, or paper with diameters of 3 inches (37.6 mm), 6 inches (152.2 mm), 8 inches (203.2 mm), etc., can be used.

[0172] The biaxially oriented polyester film 8 can be used for a variety of applications. For example, it can be suitably used as packaging containers, labels (e.g., labels for wrapping PET bottles), and outer films for electronic components, including lithium-ion battery casings. It is particularly suitable for use in packaging containers, and especially in food packaging containers.

[0173] <3. Laminate> As shown in Figure 2, in one embodiment, the laminate 9 includes a biaxially oriented polyester film 8 and a sealant layer 21. Because the laminate 9 includes a sealant layer 21, products containing the laminate 9 (e.g., packaging containers) can be manufactured by heat sealing.

[0174] The sealant layer 21 is a layer that can be softened at a lower temperature than the biaxially oriented polyester film 8. That is, the sealant layer 21 can be melted at a lower temperature than the biaxially oriented polyester film 8. The sealant layer 21 may be formed, for example, with a hot melt adhesive, with a film, or with other materials. Examples of materials constituting the sealant layer 21 include thermoplastic resins. Examples of materials constituting the sealant layer 21 include polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), polypropylene resins, ethylene-vinyl acetate copolymers, ethylene-α-olefin random copolymers, and ionomer resins. The sealant layer 21 may contain one of these, or two or more.

[0175] Furthermore, biomass polyethylene is preferred as polyethylene from the viewpoint of further reducing the environmental burden. Biomass polyethylene is polyethylene manufactured using biomass ethanol as a raw material. In particular, biomass polyethylene manufactured using biomass-derived fermented ethanol obtained from plant materials is preferred. Examples of plant materials include corn, sugarcane, beets, and manioc.

[0176] The sealant layer 21 may contain additives. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, color inhibitors, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, friction reducers, slip agents, mold release agents, antioxidants, ion exchange agents, antiblocking agents, and colorants.

[0177] The thickness of the sealant layer 21 may be, for example, 5 μm or more, or 7 μm or more. The thickness of the sealant layer 21 may be, for example, 50 μm or less, or 30 μm or less. The sealant layer 21 may be a single layer or a two-layer or more layer configuration.

[0178] As shown in Figure 3, the laminate 9 may further include a printed layer 11. The laminate 9 may include the printed layer 11, a biaxially oriented polyester film 8, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the biaxially oriented polyester film 8, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9.

[0179] The printing layer 11, or ink layer 11, can impart a design to the laminate 9. The design may be a graphic, such as a pattern, design, picture, photograph, or figure, or a symbol, such as letters, symbols, or emblems, or any combination of two or more of these. The design may also be plain.

[0180] The shape of the printed layer 11 when the laminate 9 is viewed in the perpendicular direction can be set as appropriate. When the laminate 9 is viewed in the perpendicular direction, the size of the printed layer 11 may be the same as the size of the biaxially oriented polyester film 8, or it may be smaller than the biaxially oriented polyester film 8.

[0181] The printed layer 11 may contain a resin. Examples of resins include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures of two or more of these. The printed layer 11 may contain a coloring agent. Examples of coloring agents include pigments and dyes. The printed layer 11 may contain additives. Examples of additives include antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, stabilizers, lubricants, defoaming agents, crosslinking agents, anti-blocking agents, and antioxidants.

[0182] The printed layer 11 can be formed with ink. In addition to the components described above, the ink may also contain, for example, a solvent. The ink may also be made using biomass-derived raw materials.

[0183] The printed layer 11 can be formed by printing and drying ink. Examples of printing methods include offset printing, gravure printing, and screen printing. Examples of drying methods after printing include hot air drying, hot roll drying, and infrared drying.

[0184] The laminate 9 may further include a paper layer. For example, the laminate 9 may include a paper layer between the biaxially oriented polyester film 8 and the printed layer 11, or a paper layer between the printed layer 11 and the sealant layer 21. In particular, it is preferable to include a paper layer between the biaxially oriented polyester film 8 and the printed layer 11. In this case, in at least a portion of the laminate 9, the biaxially oriented polyester film 8, the paper layer, the printed layer 11, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9 (not shown).

[0185] For the paper layer, for example, fine paper, art paper, coated paper, resin-coated paper, cast-coated paper, cardboard, synthetic paper, impregnated paper, etc., can be used. The thickness of the paper layer can be, for example, 30 g / m². 2 More than 400g / m 2 The following is preferable:

[0186] The paper layer can be laminated onto the biaxially oriented polyester film 8 via other layers (for example, an adhesive layer, an adhesive resin layer, or an anchor coat layer).

[0187] The adhesive layer can be formed with an adhesive, i.e., a laminating adhesive. For example, it can be formed by applying a laminating adhesive to a biaxially oriented polyester film 8 and / or paper layer and drying it. The laminating adhesive may be a one-component curing type or a two-component curing type. The laminating adhesive may be solvent-based, water-based, or emulsion-based. Examples of laminating adhesives include vinyl adhesives, (meth)acrylic adhesives, polyamide adhesives, polyester adhesives, polyether adhesives, polyurethane adhesives, epoxy adhesives, and rubber adhesives. These may be used individually or in combination of two or more types.

[0188] The thickness of the adhesive layer may be, for example, 0.1 μm or more, or 1 μm or more. The thickness of the adhesive layer may be, for example, 10 μm or less, or 5 μm or less.

[0189] The adhesive resin layer contains a thermoplastic resin. Examples of thermoplastic resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-maleic acid copolymer, and ionomer resins. In addition, resins obtained by graft polymerization and / or copolymerization of at least one of an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, or ester monomer with a polyolefin resin can also be used. Resins obtained by graft-modifying a polyolefin resin with maleic anhydride can also be used. These may be used individually or in combination of two or more.

[0190] The thickness of the adhesive resin layer may be, for example, 0.1 μm or more, 1 μm or more, 5 μm or more, or 10 μm or more. The thickness of the adhesive resin layer may be, for example, 100 μm or less, 50 μm or less, 10 μm or less, or 5 μm or less.

[0191] The anchor coat layer can be formed from a composition containing a resin and a curing agent. Examples of resins include urethane, polyester, acrylic, titanium, isocyanate, imine, and polybutadiene resins. Among these, urethane, polyester, and acrylic resins are preferred. Urethane resins are preferred from the viewpoint of adhesion. On the other hand, acrylic resins are preferred from the viewpoint of water resistance. These may be used individually or in combination of two or more. Examples of curing agents include epoxy, isocyanate, and melamine curing agents. These may be used individually or in combination of two or more.

[0192] The composition for forming the anchor coat layer preferably contains a silane coupling agent. The silane coupling agent preferably has one or more organic functional groups in its molecule. If the silane coupling agent has multiple (i.e., one or more) organic functional groups in its molecule, the multiple organic functional groups may be the same or different. In other words, the multiple organic functional groups can be independent of each other. Examples of organic functional groups include alkoxy groups, amino groups, epoxy groups, and isocyanate groups.

[0193] The composition for forming the anchor coat layer may contain a solvent. Examples of solvents include aromatic solvents such as benzene and toluene, alcoholic solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, esteric solvents such as ethyl acetate and butyl acetate, and polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.

[0194] The anchor coat layer can be formed by applying a composition for forming the anchor coat layer to a biaxially oriented polyester film 8 and drying it.

[0195] The thickness of the anchor coat layer may be, for example, 0.1 μm or more, or 0.2 μm or more. The thickness of the anchor coat layer may be, for example, 2 μm or less, or 1 μm or less.

[0196] As shown in Figure 4A, the laminate 9 may further include an inorganic thin film layer 31, i.e., a vapor-deposited layer 31. For example, the laminate 9 may include a printed layer 11, a biaxially oriented polyester film 8, an inorganic thin film layer 31, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the biaxially oriented polyester film 8, the inorganic thin film layer 31, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9. Because the laminate 9 includes an inorganic thin film layer 31, its gas barrier properties can be improved.

[0197] The inorganic thin film layer 31 may contain inorganic oxides. Examples of inorganic oxides include oxides of silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), and yttrium (Y). Preferred materials for forming the inorganic thin film layer 31 are silicon oxide (i.e., silica), aluminum oxide (i.e., alumina), and mixtures of silicon oxide and aluminum oxide. Among these, a composite oxide of silicon oxide and aluminum oxide is more preferred because it allows for both flexibility and density of the inorganic thin film layer 31. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably 20% by mass or more and 70% by mass or less of Al, based on the mass ratio in terms of metal atoms. If it is 20% by mass or more, it exhibits excellent gas barrier properties. If the silicon dioxide content is 70% by mass or less, it is possible to prevent the inorganic thin film layer 31 from becoming excessively hard. Here, silicon dioxide refers to various silicon oxides such as SiO and SiO2 or mixtures thereof, and aluminum oxide refers to various aluminum oxides such as AlO and Al2O3 or mixtures thereof.

[0198] The inorganic thin film layer 31 may be a metal vapor-deposited layer. Examples of metals that can be used for the metal vapor-deposited layer include magnesium, aluminum, titanium, chromium, iron, nickel, copper, zinc, silver, tin, platinum, and gold. Among these, aluminum is preferred. In other words, it is preferable that the inorganic thin film layer 31 be an aluminum vapor-deposited layer.

[0199] The thickness of the inorganic thin film layer 31 may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, or 20 nm or more. The thickness of the inorganic thin film layer 31 may be, for example, 200 nm or less, 100 nm or less, or 50 nm or less.

[0200] The inorganic thin film layer 31 may be a single layer or a multi-layer structure. If the inorganic thin film layer 31 consists of two or more layers, those layers may be independent of each other in terms of composition and physical properties (e.g., thickness).

[0201] The inorganic thin film layer 31 can be formed by physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or by chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. When forming a silicon oxide-aluminum oxide thin film by vacuum deposition, for example, a mixture of SiO2 and Al2O3, or a mixture of SiO2 and Al can be used as the deposition raw material. These deposition materials are preferably in particulate form. The particle size should be such that the pressure during deposition does not change. For example, a particle diameter of 1 mm to 5 mm is preferred. For heating, methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be employed. It is also possible to employ reactive deposition using methods such as introducing oxygen, nitrogen, hydrogen, argon, carbon dioxide, or water vapor as a reaction gas, or using ozone addition or ion assistance. Furthermore, the film deposition conditions can be arbitrarily changed, such as applying a bias to the substrate (the laminated film to be deposited) or heating or cooling the substrate. These deposition materials, reaction gases, bias of the substrate, and heating / cooling can also be changed in the same way when using sputtering or CVD methods.

[0202] As shown in Figure 4B, the laminate 9 may include a biaxially oriented polyester film 8, an inorganic thin film layer 31, and a sealant layer 21. In at least a portion of the laminate 9, the biaxially oriented polyester film 8, the inorganic thin film layer 31, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9.

[0203] As shown in Figure 5A, the laminate 9 may further include an anchor coat layer 32, i.e., a coating layer 32. For example, the laminate 9 may include a printed layer 11, a biaxially oriented polyester film 8, an anchor coat layer 32, an inorganic thin film layer 31, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the biaxially oriented polyester film 8, the anchor coat layer 32, the inorganic thin film layer 31, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9. The anchor coat layer 32 can connect the biaxially oriented polyester film 8 and the inorganic thin film layer 31.

[0204] Although the term "anchor coat layer," which encompasses the anchor coat layer 32, has already been explained, additional explanation is provided because there are preferred examples specific to the anchor coat layer 32.

[0205] The anchor coat layer 32 can be formed from a composition containing a resin and a curing agent. Examples of resins include urethane, polyester, acrylic, titanium, isocyanate, imine, and polybutadiene resins. Among these, urethane, polyester, and acrylic resins are preferred. Urethane resins are preferred from the viewpoint of adhesion. On the other hand, acrylic resins are preferred from the viewpoint of water resistance. These may be used individually or in combination of two or more. Examples of curing agents include epoxy, isocyanate, and melamine curing agents. These may be used individually or in combination of two or more.

[0206] The composition for forming the anchor coat layer 32 preferably contains a silane coupling agent. The silane coupling agent preferably has one or more organic functional groups in its molecule. If the silane coupling agent has multiple (i.e., one or more) organic functional groups in its molecule, the multiple organic functional groups may be the same or different. In other words, the multiple organic functional groups can be independent of each other. Examples of organic functional groups include alkoxy groups, amino groups, epoxy groups, and isocyanate groups.

[0207] The composition for forming the anchor coat layer 32 preferably contains a resin containing oxazoline groups, that is, a polymer containing oxazoline groups. Oxazoline groups have a high affinity for the inorganic thin film layer 31 and can react with oxygen-deficient portions of inorganic oxides and metal hydroxides that may be generated during the formation of the inorganic thin film layer 31, thus enabling strong adhesion to the inorganic thin film layer 31. In addition, unreacted oxazoline groups present in the anchor coat layer 32 can react with carboxylic acid terminals that may be generated in the biaxially oriented polyester film 8 and the anchor coat layer 32 (for example, carboxylic acid terminals that may be generated by hydrolysis), thereby enabling the formation of crosslinks.

[0208] The composition for forming the anchor coat layer 32 may contain a solvent. Examples of solvents include aromatic solvents such as benzene and toluene, alcoholic solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, esteric solvents such as ethyl acetate and butyl acetate, and polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.

[0209] The anchor coat layer 32 can be formed by applying a composition for forming the anchor coat layer 32 to the biaxially oriented polyester film 8 and drying it.

[0210] As shown in Figure 5B, the laminate 9 may include a biaxially oriented polyester film 8, an anchor coat layer 32, an inorganic thin film layer 31, and a sealant layer 21. In at least a portion of the laminate 9, the biaxially oriented polyester film 8, the anchor coat layer 32, the inorganic thin film layer 31, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9.

[0211] As shown in Figure 6A, the laminate 9 may further include a protective layer 33 on top of the inorganic thin film layer 31. That is, the laminate 9 may further include a protective layer 33 adjacent to the inorganic thin film layer 31. For example, the laminate 9 may include a printed layer 11, a biaxially oriented polyester film 8, an anchor coat layer 32, an inorganic thin film layer 31, a protective layer 33, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the biaxially oriented polyester film 8, the anchor coat layer 32, the inorganic thin film layer 31, the protective layer 33, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9. The laminate 9 can suppress or reduce gas permeation by including the protective layer 33. The protective layer 33 plays a role in improving the gas barrier properties of the laminate 9.

[0212] The gas barrier properties of the laminate 9 can be improved by forming the protective layer 33 with a composition containing a resin and a curing agent. This will be explained below. Generally, the inorganic thin film layer 31 has minute defects scattered throughout. By coating such a composition onto the inorganic thin film layer 31 to form the protective layer 33, the composition can penetrate into the defects in the inorganic thin film layer 31, and as a result, the gas barrier properties of the laminate 9 can be improved.

[0213] Examples of resins include urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins. These may be used individually or in combination of two or more. Examples of curing agents include epoxy-based, isocyanate-based, and melamine-based curing agents. These may be used individually or in combination of two or more.

[0214] Among these, urethane resins, i.e., urethane resins, are preferred. In urethane resins, the polar groups of the urethane bonds interact with the inorganic thin film layer 31, and the amorphous portion in the urethane resin exhibits flexibility, thus suppressing damage to the inorganic thin film layer 31 when a bending load is applied.

[0215] The acid value of the urethane resin is preferably in the range of 10 mg KOH / g to 60 mg KOH / g. More preferably, it is in the range of 15 mg KOH / g to 55 mg KOH / g, and even more preferably, in the range of 20 mg KOH / g to 50 mg KOH / g. When the acid value of the urethane resin is within the above range, the liquid stability is improved when it is dispersed in water, and the protective layer 33 can be uniformly deposited on a highly polar inorganic thin film, resulting in a good coating appearance.

[0216] The urethane resin preferably has a glass transition temperature (Tg) of 80°C or higher, and more preferably 90°C or higher. By setting the Tg to 80°C or higher, swelling of the protective layer 33 due to molecular motion during the moist heat treatment process (heating up, heat retention, cooling down) can be reduced.

[0217] From the viewpoint of improving gas barrier properties, urethane resins preferably contain aromatic or aromatic aliphatic diisocyanate components as their main constituents. Among these, the inclusion of metaxylylene diisocyanate components is particularly preferable. By using such a urethane resin, the cohesive force of the urethane bonds can be further enhanced by the stacking effect between aromatic rings, resulting in good gas barrier properties.

[0218] It is preferable that the proportion of aromatic or aromatic aliphatic diisocyanates in the urethane resin be in the range of 50 mol% or more (i.e., 50 mol% to 100 mol%) of 100 mol% of the polyisocyanate component. The total proportion of aromatic or aromatic aliphatic diisocyanates is preferably 60 mol% to 100 mol%, more preferably 70 mol% to 100 mol%, and even more preferably 80 mol% to 100 mol%. As such a resin, the "Takelac® WPB" series, commercially available from Mitsui Chemicals, Inc., can be suitably used. When the total proportion of aromatic or aromatic aliphatic diisocyanates is 50 mol% or more, good gas barrier properties can be obtained.

[0219] From the viewpoint of improving affinity with the inorganic thin film layer 31, it is preferable that the urethane resin has a carboxylic acid group (carboxyl group). To introduce a carboxylic acid (salt) group into the urethane resin, for example, a polyol compound having a carboxylic acid group, such as dimethylolpropionic acid or dimethylolbutanoic acid, can be introduced as a copolymer component. Alternatively, after synthesizing the carboxylic acid group-containing urethane resin, a water-dispersible urethane resin can be obtained by neutralizing it with a salt-forming agent. Examples of salt-forming agents include ammonia, trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine, N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine, and N-dialkylalkanolamines such as N-dimethylethanolamine and N-diethylethanolamine. These may be used individually or in combination of two or more.

[0220] The composition for forming the protective layer 33 may contain a solvent. Examples of solvents include aromatic solvents such as benzene and toluene, alcoholic solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, esteric solvents such as ethyl acetate and butyl acetate, and polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.

[0221] Alternatively, the protective layer 33 may be formed by a composition polycondensed by a sol-gel method. This allows for the formation of a protective layer 33 with high gas barrier properties, thereby improving the gas barrier properties of the laminate 9. Such a composition may include an alkoxide represented by formula 1 and at least one of a polyvinyl alcohol resin and an ethylene-vinyl alcohol copolymer. Formula 1 R 1 n M(OR 2 ) m R 1 R represents an organic group with 1 to 8 carbon atoms. 2 * represents an organic group with 1 to 8 carbon atoms. M represents a metal atom. n represents a non-negative integer. m represents a non-negative integer. n+m represents the valence of M. Note that in Equation 1, R 1 If there are multiple R 1 Each of these can be independent. In Equation 1, R 2 If there are multiple R 2 Each of these can be independent.

[0222] As the alkoxide represented by Formula 1, at least one of the following can be used: a partially hydrolyzed alkoxide or a condensate of hydrolyzed alkoxide. The partially hydrolyzed alkoxide does not need to have all of its alkoxy groups hydrolyzed. As the condensate of hydrolyzed alkoxide, dimers or more of the partially hydrolyzed alkoxide, specifically 2 to 6-mers, can be used.

[0223] Examples of the metal atom represented by M include silicon, zirconium, titanium, and aluminum. Among these, silicon and titanium are preferred. Note that alkoxides of a single or two or more different metal atoms may be mixed and used.

[0224] R 1 Examples of the organic group having 1 to 8 carbon atoms represented by R include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, and n-octyl group.

[0225] R 2 Examples of the organic group represented by R include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, and n-octyl group.

[0226] This composition may contain a silane coupling agent. Examples of the silane coupling agent include organoalkoxysilanes containing an organic reactive group. In particular, organoalkoxysilanes having an epoxy group are preferred. Examples of the organoalkoxysilane having an epoxy group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Note that these may be used alone or in combination of two or more.

[0227] Note that this composition may further contain, for example, a sol-gel method catalyst, an acid, water, and an organic solvent.

[0228] As shown in Figure 6B, the laminate 9 may include a biaxially oriented polyester film 8, an anchor coat layer 32, an inorganic thin film layer 31, a protective layer 33, and a sealant layer 21. In at least a portion of the laminate 9, the biaxially oriented polyester film 8, the anchor coat layer 32, the inorganic thin film layer 31, the protective layer 33, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9.

[0229] As shown in Figure 7, the laminate 9 may further include a sealant layer 22. For example, the laminate 9 may include a sealant layer 22, a biaxially oriented polyester film 8, and a sealant layer 21. In at least a portion of the laminate 9, the sealant layer 22, the biaxially oriented polyester film 8, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9. Of course, the laminate 9 having the laminate configuration shown in Figures 3 to 6B may further include a sealant layer 22. It is preferable that one of the two sides of the laminate 9 is composed of a sealant layer 21 and the other side is composed of a sealant layer 22. That is, it is preferable that one of the pair of outermost layers of the laminate 9 is a sealant layer 21 and the other outermost layer is a sealant layer 22. The description of the sealant layer 22 is omitted because it overlaps with the description of the sealant layer 21. Therefore, the description of the sealant layer 21 can also be treated as a description of the sealant layer 22.

[0230] Figures 3, 4A, 5A, and 6A illustrate a configuration in which the printed layer 11, the biaxially oriented polyester film 8, and the sealant layer 21 are arranged in this order along the thickness direction of the laminate 9. However, of course, they do not have to be arranged in that order.

[0231] For example, as shown in Figure 8, in at least a portion of the laminate 9, the biaxially oriented polyester film 8, the printing layer 11, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the biaxially oriented polyester film 8, the printing layer 11, and the sealant layer 21.

[0232] As shown in Figure 9, in at least a portion of the laminate 9, the biaxially oriented polyester film 8, the printed layer 11, the inorganic thin film layer 31, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the biaxially oriented polyester film 8, the printed layer 11, the inorganic thin film layer 31, and the sealant layer 21.

[0233] As shown in Figure 10, in at least a portion of the laminate 9, the biaxially oriented polyester film 8, the printed layer 11, the anchor coat layer 32, the inorganic thin film layer 31, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the biaxially oriented polyester film 8, the printed layer 11, the anchor coat layer 32, the inorganic thin film layer 31, and the sealant layer 21.

[0234] As shown in Figure 11, in at least a portion of the laminate 9, the biaxially oriented polyester film 8, the printing layer 11, the anchor coat layer 32, the inorganic thin film layer 31, the protective layer 33, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the biaxially oriented polyester film 8, the printing layer 11, the anchor coat layer 32, the inorganic thin film layer 31, the protective layer 33, and the sealant layer 21.

[0235] As shown in Figure 12, the laminate 9 may further include a sealant layer 22. For example, the laminate 9 may include a sealant layer 22, a biaxially oriented polyester film 8, a printed layer 11, and a sealant layer 21. In at least a portion of the laminate 9, the sealant layer 22, the biaxially oriented polyester film 8, the printed layer 11, and the sealant layer 21 can be arranged in this order in the thickness direction of the laminate 9. Of course, the laminate 9 having the laminate configuration shown in Figures 9 to 11 may further include a sealant layer 22. It is preferable that one of the two sides of the laminate 9 is composed of a sealant layer 21 and the other side is composed of a sealant layer 22. That is, it is preferable that one of the pair of outermost layers of the laminate 9 is a sealant layer 21 and the other outermost layer is a sealant layer 22.

[0236] The role of the biaxially oriented polyester film 8 in the laminate 9 is not particularly limited. For example, the biaxially oriented polyester film 8 may play a role in holding the aforementioned layers (e.g., sealant layer 21, printed layer 11, inorganic thin film layer 31), that is, it may play a role as a substrate. On the other hand, the biaxially oriented polyester film 8 may be used not as a substrate, but for the purpose of improving some physical property of the laminate 9, such as strength. In other words, the biaxially oriented polyester film 8 used for that purpose plays a role as a support. Furthermore, when the biaxially oriented polyester film 8 acts as a support, other layers (for example, a resin film or a paper layer) can act as substrates.

[0237] Furthermore, when the biaxially oriented polyester film 8 serves as the base material, the laminate 9 may further include a layer that serves as a support (hereinafter referred to as the "support layer"). On the other hand, when the biaxially oriented polyester film 8 serves as the support (i.e., is the support layer), the laminate 9 may further include a layer that serves as the base material (hereinafter referred to as the "base material layer").

[0238] Figures 2 to 12 have described the laminate 9 focusing on the biaxially oriented polyester film 8. From here on, however, we will describe the laminate 9 focusing on the substrate layer and support layer rather than the biaxially oriented polyester film 8. In other words, we will explain the laminate 9 from a different perspective. Therefore, there may be some overlap in the explanation from here on with the explanations given so far.

[0239] As shown in Figure 13, the laminate 9 includes a base layer 51 and a sealant layer 21. Because the laminate 9 includes a sealant layer 21, products containing the laminate 9 (e.g., packaging containers) can be manufactured by heat sealing.

[0240] A biaxially oriented polyester film 8 is used as the base layer 51. That is, the base layer 51 is a biaxially oriented polyester film 8. On the other hand, the base layer 51 may be a single layer or a two-layer or more layer configuration. For example, the base layer 51 may be a laminated configuration of a biaxially oriented polyester film 8 and a resin film (for example, a biaxially oriented nylon film).

[0241] As shown in Figure 14, the laminate 9 may further include a printed layer 11. The laminate 9 may include a printed layer 11, a substrate layer 51, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the substrate layer 51, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9.

[0242] As shown in Figure 15A, the laminate 9 may further include an intermediate layer 61. For example, the laminate 9 may include a printed layer 11, a substrate layer 51, an intermediate layer 61, and a sealant layer 21. In at least a portion of the laminate 9, the printed layer 11, the substrate layer 51, the intermediate layer 61, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9.

[0243] The intermediate layer 61 may include a support layer, a gas barrier layer, or a metal foil, and may include two or more of these. Of course, it may also include other layers, such as an adhesive layer, an adhesive resin layer, or an anchor coat layer. The intermediate layer 61 may also include the printing layer 11. By including a support layer in the intermediate layer 61, some physical properties of the laminate 9, such as strength, can be improved. By including a gas barrier layer or a metal foil in the intermediate layer 61, the gas barrier properties of the laminate 9 can be improved.

[0244] Examples of the support layer include a resin film and a paper layer. Examples of the resin film include a film containing one or more resin materials such as polyester, (meth)acrylic resin, polyolefin (e.g., polyethylene, polypropylene, polymethylpentene), vinyl resin, cellulose resin, ionomer resin, polyamide (nylon 6, nylon 6,6, poly(m-xylene adipamide) (MXD6)), etc. Among them, polyester is preferred. That is, the resin film preferably contains polyester. The resin film may be a stretched resin film or an unstretched resin film. The stretched resin film may be a uniaxially stretched resin film or a biaxially stretched resin film. Among them, a biaxially stretched resin film is preferred because of its excellent dimensional stability.

[0245] The support layer can contain additives. Examples of the additives include an oxygen absorber, a plasticizer, an ultraviolet stabilizer, an antioxidant, an anti-coloring agent, a matting agent, a deodorant, a flame retardant, a weathering agent, an antistatic agent, a friction reducer, a slip agent, a release agent, an antioxidant, an ion exchanger, an antiblocking agent, and a coloring agent.

[0246] A biaxially oriented polyester film 8 may be used as the support layer. That is, the support layer may be a biaxially oriented polyester film 8.

[0247] When a biaxially oriented polyester film 8 is used as the support layer, as the base layer 51, a biaxially oriented polyester film 8, a resin film, or a paper layer may be used. Thus, when a biaxially oriented polyester film 8 is used as the support layer, it is not necessary to use a biaxially oriented polyester film 8 as the base layer 51.

[0248] When a biaxially oriented polyester film 8 is used as the support layer, the base layer 51 can be, for example, the biaxially oriented polyester film 8, a resin film other than the biaxially oriented polyester film 8, or a paper layer. As the resin film, for example, a film containing one or more resin materials such as polyester, (meth)acrylic resin, polyolefin (e.g., polyethylene, polypropylene, polymethylpentene), vinyl resin, cellulose resin, ionomer resin, or polyamide (nylon 6, nylon 6,6, polymetaxylylene adipamide (MXD6)) can be used. Polyester is preferred among these. In other words, it is preferable that the resin film contains polyester. The resin film may be a stretched resin film or an unstretched resin film. As the stretched resin film, it may be a uniaxially oriented resin film or a biaxially oriented resin film. Among these, a biaxially oriented resin film is preferred for its excellent dimensional stability.

[0249] The intermediate layer 61 may include an anchor coat layer 32 on at least one surface of the support layer, or it may include an inorganic thin film layer 31. The intermediate layer 61 may also include a protective layer 33 (not shown).

[0250] The gas barrier layer contains a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamide (e.g., nylon 6, nylon 6,6, polymethaxylylene adipamide (MXD6)), polyester, polyurethane, and (meth)acrylic resin. The gas barrier layer may contain two or more gas barrier resins. The gas barrier layer may further contain other resins and additives.

[0251] The thickness of the gas barrier layer may be, for example, 3 μm or more, 5 μm or more, or 7 μm or more. The thickness of the gas barrier layer may be, for example, 30 μm or less, or 20 μm or less.

[0252] Examples of metal foils include aluminum foil and magnesium foil. Of these, aluminum foil is preferred. In particular, aluminum foil containing iron is preferred from the viewpoint of pinhole resistance and ductility. The iron content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, per 100% by mass of aluminum foil. On the other hand, the iron content is preferably 9.0% by mass or less, and more preferably 2.0% by mass or more.

[0253] The metal foil may be pre-treated. Examples of pre-treatment include degreasing, acid cleaning, and alkaline cleaning.

[0254] The thickness of the metal foil may be, for example, 3 μm or more, or 6 μm or more. The thickness of the metal foil may be, for example, 100 μm or less, or 25 μm or less.

[0255] Here, we have described a configuration in which, in at least a portion of the laminate 9, the printed layer 11, the base layer 51, the intermediate layer 61, and the sealant layer 21 are arranged in this order in the thickness direction of the laminate 9. However, the printed layer 11, the intermediate layer 61, the base layer 51, and the sealant layer 21 may also be arranged in this order in the thickness direction of the laminate 9 (not shown).

[0256] As shown in Figure 15B, the laminate 9 may include a base layer 51, an intermediate layer 61, and a sealant layer 21. In at least a portion of the laminate 9, the base layer 51, the intermediate layer 61, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9.

[0257] Figures 14 and 15A illustrate a configuration in which the printed layer 11, the substrate layer 51, and the sealant layer 21 are arranged in that order along the thickness direction of the laminate 9. However, of course, they do not have to be arranged in that order.

[0258] For example, as shown in Figure 16, in at least a portion of the laminate 9, the base layer 51, the printing layer 11, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the base layer 51, the printing layer 11, and the sealant layer 21.

[0259] As shown in Figure 17A, in at least a portion of the laminate 9, the base layer 51, the printing layer 11, the intermediate layer 61, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the base layer 51, the printing layer 11, the intermediate layer 61, and the sealant layer 21.

[0260] As shown in Figure 17B, in at least a portion of the laminate 9, the base layer 51, the intermediate layer 61, and the sealant layer 21 may be arranged in this order in the thickness direction of the laminate 9. The laminate 9 may include the base layer 51, the intermediate layer 61, and the sealant layer 21.

[0261] The laminate 9 having the laminated structure shown in Figures 13 to 17B may further include a sealant layer 22 (not shown). It is preferable that one of the two surfaces of the laminate 9 is composed of a sealant layer 21 and the other surface is composed of a sealant layer 22. In other words, it is preferable that one of the pair of outermost layers of the laminate 9 is a sealant layer 21 and the other outermost layer is a sealant layer 22.

[0262] Up to this point, the laminate 9 has been described as having a sealant layer 21 and, optionally, a sealant layer 22, but of course, it is not limited to this configuration. The laminate 9 may also include an adhesive layer instead of at least one of the sealant layer 21 and the sealant layer 22. The adhesive layer can be formed by an adhesive. Examples of adhesives include synthetic rubbers such as styrene-butadiene rubber, acrylonitrile-butadiene rubber, and polyisobutylene rubber, as well as natural rubber, acrylic resins, silicone resins, and polypropylene. These may be used individually or in combination of two or more.

[0263] Thus, the laminate 9 is It comprises a base layer 51 and a sealant layer 21 or an adhesive layer, The base layer 51 may include a biaxially oriented polyester film 8.

[0264] Meanwhile, the laminate 9 is, It comprises a base layer 51, an intermediate layer 61, and a sealant layer 21 or an adhesive layer. The intermediate layer 61 may also contain a biaxially oriented polyester film 8.

[0265] The laminate 9 has been explained above with reference to Figures 2 to 17B. Now, let's look at some more specific examples. Before that, the meanings of the abbreviations are given below. CRF Biaxially Oriented Polyester Film 8 PET (Polyethylene Terephthalate) ONY (Stretched Nylon) OPP (Stretched Polypropylene) CPP (Unstretched Polypropylene) PVC (Polyvinyl Chloride) PE (Polyethylene) PEF polyethylene film Al Aluminum MO metal oxides MOR Metal Alkoxide

[0266] Let's look at a specific example. In this example, the base layer 51 is a biaxially oriented polyester film 8. (1) Substrate layer (CRF) / Adhesive layer / Heat seal layer (PEF) (2) Base material layer (CRF) / Heat seal layer (PE) (3) Base material layer (CRF) / Anchor coat layer / Heat seal layer (PE) (4) Substrate layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (5) Base material layer (CRF) / adhesive layer (6) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Heat seal layer (PEF) (7) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Heat seal layer (PE) (8) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Anchor coat layer / Heat seal layer (PE) (9) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (10) Base material layer (CRF) / Inorganic thin film layer (Al) / Adhesive layer (11) Substrate layer (CRF) / Inorganic thin film layer (Al) / Heat seal layer (PE) (12) Substrate layer (CRF) / Inorganic thin film layer (Al) / Anchor coat layer / Heat seal layer (PE)

[0267] Let's look at some more specific examples. In these examples as well, the base layer 51 is a biaxially oriented polyester film 8. (1) Substrate layer (CRF) / Printing layer / Adhesive layer / Heat seal layer (PEF) (2) Substrate layer (CRF) / Printing layer / Heat seal layer (PE) (3) Substrate layer (CRF) / Printing layer / Anchor coat layer / Heat seal layer (PE) (4) Substrate layer (CRF) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (5) Base material layer (CRF) / printing layer / adhesive layer (6) Printing layer / base material layer (CRF) / inorganic thin film layer (Al) / adhesive layer (7) Printing layer / Substrate layer (CRF) / Inorganic thin film layer (Al) / Heat seal layer (PE) (8) Printing layer / Substrate layer (CRF) / Inorganic thin film layer (Al) / Anchor coat layer / Heat seal layer (PE)

[0268] Let's look at some more specific examples. In these examples as well, the base layer 51 is a biaxially oriented polyester film 8. (1) Substrate layer (CRF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (PEF) (2) Substrate layer (CRF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (CPP) (3) Substrate layer (CRF) / Adhesive layer / Inorganic thin film layer (Al) / Support layer (PET) / Adhesive layer / Heat seal layer (PEF) (4) Substrate layer (CRF) / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (PEF) (5) Substrate layer (CRF) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (6) Substrate layer (CRF) / Adhesive layer / Inorganic thin film layer (Al) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (7) Substrate layer (CRF) / Adhesive layer / Support layer (ONY) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (CPP) (8) Substrate layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Heat seal layer (PE) (9) Substrate layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Anchor coat layer / Heat seal layer (PE) (10) Substrate layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Inorganic thin film layer (Al) / Support layer (PET) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (11) Substrate layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (12) Substrate layer (CRF) / Adhesive layer / Support layer (PET) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (13) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (CPP) (14) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (PEF) (15) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (16) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Inorganic thin film layer (Al) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (17) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (ONY) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (CPP) (18) Substrate layer (CRF) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (PET) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (19) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (20) Heat seal layer (PEF) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Substrate layer (CRF) / Adhesive layer / Heat seal layer (PEF) (21) Heat seal layer (PE) / Substrate layer (CRF) / Adhesive layer / Support layer (PEF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (22) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Adhesive layer / Support layer (PEF) / Adhesive layer / Support layer (PET) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Heat seal layer (PEF) (23) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Adhesive layer / Support layer (PEF) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (PET) / Adhesive layer / Heat seal layer (PEF)

[0269] Let's look at some more specific examples. In these examples as well, the base layer 51 is a biaxially oriented polyester film 8. (1) Substrate layer (CRF) / Printing layer / Adhesive layer / Metal foil (Al) / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (PEF) (2) Substrate layer (CRF) / Printing layer / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (CPP) (3) Substrate layer (CRF) / Printing layer / Adhesive layer / Inorganic thin film layer (Al) / Support layer (PET) / Adhesive layer / Heat seal layer (PEF) (4) Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (ONY) / Adhesive layer / Heat seal layer (PEF) (5) Substrate layer (CRF) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (6) Substrate layer (CRF) / Printing layer / Adhesive layer / Inorganic thin film layer (Al) / Support layer (PET) / Adhesive layer / Heat seal layer (CPP) (7) Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (ONY) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (CPP) (8) Substrate layer (CRF) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Heat seal layer (PE) (9) Substrate layer (CRF) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Anchor coat layer / Heat seal layer (PE) (10) Substrate layer (CRF) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Inorganic thin film layer (Al) / Support layer (PET) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (11) Substrate layer (CRF) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Metal foil (Al) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (12) Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (PET) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (13) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Printing layer / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (14) Heat seal layer (PEF) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Substrate layer (CRF) / Printing layer / Adhesive layer / Heat seal layer (PEF) (15) Heat seal layer (PE) / Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (PEF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (16) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (PEF) / Adhesive layer / Support layer (PET) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Heat seal layer (PEF) (17) Heat seal layer (PEF) / Adhesive layer / Substrate layer (CRF) / Printing layer / Adhesive layer / Support layer (PEF) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (PET) / Adhesive layer / Heat seal layer (PEF)

[0270] Let's look at another specific example. In this example, the support layer is a biaxially oriented polyester film 8. (1) Substrate layer (paper) / Adhesive layer / Metal foil (Al) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PVC) (2) Substrate layer (ONY) / Adhesive layer / Support layer (CRF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (3) Substrate layer (PET) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (4) Substrate layer (paper) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (5) Substrate layer (OPP) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (6) Substrate layer (ONY) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (7) Substrate layer (PET) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (8) Substrate layer (OPP) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (9) Substrate layer (PET) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (10) Heat seal layer (PE) / base material layer (paper) / adhesive resin layer (PE) / anchor coat layer / metal foil (Al) / adhesive layer / support layer (CRF) / anchor coat layer / adhesive resin layer (PE) / heat seal layer (PEF) (11) Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Heat seal layer (PE) (12) Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (13) Substrate layer (OPP) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (OPP) (14) Substrate layer (PET) / Adhesive layer / Inorganic thin film layer (Al) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (15) Substrate layer (ONY) / Anchor coat layer / Adhesive resin layer (PE) / Inorganic thin film layer (Al) / Support layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (16) Substrate layer (paper) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (17) Substrate layer (OPP) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (18) Substrate layer (PET) / Inorganic thin film layer (MO) / Protective layer (MOR) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (19) Substrate layer (ONY) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (20) Substrate layer (PET) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (21) Substrate layer (OPP) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (22) Substrate layer (PET) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (23) Substrate layer (paper) / Adhesive resin layer (PE) / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (24) Substrate layer (OPP) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (OPP) (25) Substrate layer (PET) / Adhesive layer / Support layer (CRF) / Heat seal layer (PE) (26) Substrate layer (PET) / Adhesive layer / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (27) Heat seal layer (PE) / base material layer (paper) / adhesive resin layer (PE) / support layer (CRF) / adhesive layer / heat seal layer (PEF) (28) Heat seal layer (PE) / base material layer (paper) / adhesive resin layer (PE) / support layer (CRF) / heat seal layer (PE) (29) Heat seal layer (PE) / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE)

[0271] Let's look at some more specific examples. In these examples as well, the support layer is a biaxially oriented polyester film 8. (1) Printing layer / Substrate layer (paper) / Adhesive layer / Metal foil (Al) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PVC) (2) Substrate layer (ONY) / Printing layer / Adhesive layer / Support layer (CRF) / Adhesive layer / Metal foil (Al) / Adhesive layer / Heat seal layer (PEF) (3) Printing layer / Substrate layer (paper) / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (4) Substrate layer (OPP) / Printing layer / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (5) Substrate layer (ONY) / Printing layer / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (6) Substrate layer (PET) / Printing layer / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (7) Substrate layer (OPP) / Printing layer / Adhesive layer / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (8) Heat seal layer (PE) / Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Anchor coat layer / Metal foil (Al) / Adhesive layer / Support layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (9) Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Heat seal layer (PE) (10) Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (11) Substrate layer (OPP) / Adhesive layer / Support layer (CRF) / Printing layer / Adhesive layer / Heat seal layer (OPP) (12) Substrate layer (PET) / Printing layer / Adhesive layer / Inorganic thin film layer (Al) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (13) Substrate layer (ONY) / Printing layer / Anchor coat layer / Adhesive resin layer (PE) / Inorganic thin film layer (Al) / Support layer (CRF) / Anchor coat layer / Adhesive resin layer (PE) / Heat seal layer (PEF) (14) Printing layer / Substrate layer (paper) / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (15) Substrate layer (OPP) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (16) Substrate layer (ONY) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (17) Substrate layer (PET) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) / Hot melt layer (Hot melt adhesive) (18) Substrate layer (OPP) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (19) Substrate layer (PET) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (CPP) (20) Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Heat seal layer (PE) (21) Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (22) Substrate layer (OPP) / Printing layer / Adhesive layer / Protective layer (MOR) / Inorganic thin film layer (MO) / Support layer (CRF) / Adhesive layer / Heat seal layer (OPP) (23) Substrate layer (PET) / Adhesive layer / Printing layer / Support layer (CRF) / Heat seal layer (PE) (24) Substrate layer (PET) / Printing layer / Adhesive layer / Support layer (CRF) / Heat seal layer (PE) (25) Substrate layer (PET) / Adhesive layer / Printing layer / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (26) Substrate layer (PET) / Printing layer / Adhesive layer / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE) (27) Heat seal layer (PE) / Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Adhesive layer / Heat seal layer (PEF) (28) Heat seal layer (PE) / Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Heat seal layer (PE) (29) Heat seal layer (PE) / Printing layer / Substrate layer (paper) / Adhesive resin layer (PE) / Support layer (CRF) / Anchor coat layer / Heat seal layer (PE)

[0272] The specific examples described above include several laminates 9 in which a base layer 51 and an inorganic thin film layer 31 are adjacent to each other. In these laminates 9, an anchor coat layer 32 may be provided between the base layer 51 and the inorganic thin film layer 31.

[0273] The specific examples described above include several laminates 9 in which a support layer and an inorganic thin film layer 31 are adjacent to each other. In these laminates 9, an anchor coat layer 32 may be provided between the support layer and the inorganic thin film layer 31.

[0274] The specific examples described above include several laminates 9 that include a protective layer 33 formed from a composition containing MOR, i.e., a metal alkoxide. In these laminates 9, the protective layer 33 may be formed from a composition containing a resin and a curing agent.

[0275] Among the specific examples described above, there are several laminates 9 that include both a base layer 51 and a support layer. In these examples, both the base layer 51 and the support layer may be biaxially oriented polyester films 8.

[0276] The laminate 9 can be used for a variety of applications. For example, it can be suitably used as packaging containers, labels (for example, labels for wrapping PET bottles), and outer films for electronic components, including lithium-ion battery casings. It is particularly suitable for use as packaging containers, and especially for food packaging containers.

[0277] <4. Packaging container> The packaging container of this embodiment includes a laminate 9. That is, the packaging container of this embodiment can be manufactured using a laminate 9. Here, "the packaging container includes a laminate 9" means that if the packaging container is composed of multiple members, at least one member includes a laminate 9. Examples of packaging containers include packaging bags (i.e., pouches), lids, laminate tubes, paper containers, and paper cups (see, for example, Japanese Patent Publication No. 6984717). The packaging container may be a food packaging container or a non-food packaging container. In other words, the contents may be food or non-food. Among these, the packaging container is preferably a food packaging container.

[0278] Examples of packaging bags include standing pouches, pillow bags (i.e., gusseted bags), two-sided sealed bags, three-sided sealed bags, four-sided sealed bags, side-sealed bags, envelope-type sealed bags, pleated sealed bags, flat-bottom sealed bags, square-bottom sealed bags, and gusseted bags.

[0279] <5. Various modifications can be made to the embodiments described above.> Various modifications can be made to the embodiments described above. For example, one or more of the following modifications can be selected to modify the embodiments described above.

[0280] In the embodiments described above, the biaxially oriented polyester film 8 was described as having a three-layer structure composed of a first layer 81, a second layer 82, and a third layer 83. However, the embodiments described above are not limited to this configuration. The biaxially oriented polyester film 8 may have a single-layer structure, or a two-layer structure composed of a first layer 81 and a second layer 82. Of course, the biaxially oriented polyester film 8 may have a four-layer or more structure. [Examples]

[0281] The present invention will be described in more detail below with reference to examples and comparative examples. Hereafter, unless otherwise specified, "parts" refers to "parts by mass," and "%" refers to "mass percent." Note that the polyesters A to G described later may be collectively referred to as raw material polyesters.

[0282] <Measurement methods for each physical property> (intrinsic viscosity) 0.2 g of the sample (specifically, the raw polyester and biaxially oriented polyester film) was dissolved in 50 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (mass ratio)), and the intrinsic viscosity (IV) was measured at 30°C using an Ostwald viscometer. The unit of intrinsic viscosity is dl / g.

[0283] (Content of terephthalic acid and isophthalic acid components) The sample (specifically, the raw polyester and biaxially oriented polyester film) was dissolved in a solvent prepared by mixing chloroform D (manufactured by Eurysop) and trifluoroacetic acid-D1 (manufactured by Eurysop) in a 10:1 volume ratio. The proton NMR of this sample solution was measured using a nuclear magnetic resonance (NMR) spectrometer ("GEMINI-200," manufactured by Varian) at a temperature of 23°C and with 64 cumulative measurements. In this NMR measurement, the peak intensity of a predetermined proton was calculated, and then the content (mol%) of terephthalic acid and isophthalic acid components in 100 mol% of the acid component was determined.

[0284] (Quantitative analysis of magnesium) The samples (specifically, the raw polyester and biaxially oriented polyester film) were decomposed by ashing in a platinum crucible, and then 6 mol / L hydrochloric acid was added and evaporated to dryness. This was then dissolved in 1.2 mol / L hydrochloric acid, and the magnesium content was quantified using an inductively coupled plasma (ICP) emission spectrometer (Shimadzu Corporation "ICPS-2000").

[0285] (Quantitative analysis of phosphorus) Phosphorus was converted to orthophosphoric acid by either dry ashing decomposition of the sample (specifically, the raw polyester and biaxially oriented polyester film) in the presence of sodium carbonate, or by wet decomposition using either a sulfuric acid / nitric acid / perchloric acid system or a sulfuric acid / hydrogen peroxide system. Next, molybdate salts were reacted in a 1 mol / L sulfuric acid solution to form phosphomolybdic acid, which was then reduced with hydrazine sulfate. The absorbance of the resulting heteropoly blue at 830 nm was measured using a spectrophotometer (Shimadzu Corporation "UV-150-02") (i.e., colorimetric quantification was performed).

[0286] (Melting Resistivity) The sample (specifically, the raw polyester and biaxially oriented polyester film) was melted at 285°C, a pair of electrode plates were inserted, and a voltage of 120V was applied. The current was measured, and the melting resistivity Si (Ω·cm) was calculated based on the following formula. Si = (A / I) × (V / io) Here, A is the area of ​​the electrode (cm²) 2 ) where I is the distance between electrodes (cm), V is the voltage (V), and io is the current (A).

[0287] (Area ratio of regions with a molecular weight of 1000 or less) 10 g of the sample (specifically, the raw polyester and biaxially oriented polyester film) was placed in a 30 mL vial and weighed. A mixture of chloroform / HFIP = 98 / 2 (volume ratio) was added to this vial and allowed to stand for 12 hours to dissolve the sample. Next, this was diluted with chloroform / hexafluoroisopropanol (HFIP) = 98 / 2 (volume ratio) to prepare a 0.1% solution. The 0.1% solution was filtered through a 0.45 μm filter (GL Chromatodisk non-aqueous N-type 13N, GL Sciences). Gel permeation chromatography (GPC) was performed on the filtrate under the following conditions. Columns used: TSKgel SuperHM-H x 2 and TSKgel SuperH2000, manufactured by Tosoh Corporation. Column temperature: 40℃ Mobile phase: Chloroform / HFIP = 98 / 2 (volume ratio) Flow rate: 0.6mL / min Injection volume: 20μL Detection: 254nm (UV-Vis detector) Molecular weight calibration: Monodisperse polystyrene (manufactured by Tosoh Corporation) Equipment: HLC-8300GPC manufactured by Tosoh Corporation The area percentage of the region with a molecular weight of 1000 or less was determined from the molecular weight distribution curve obtained by GPC measurement. While it is common practice to exclude areas outside the calibration curve from the calculation range in GPC analysis, in this analysis, in order to more accurately determine the area ratio of the region with a molecular weight of 1000 or less, the GPC chromatogram area (i.e., total peak area) was calculated including both areas inside and outside the calibration curve.

[0288] (Thickness) The thickness of the biaxially oriented polyester film was measured using a dial gauge in accordance with JIS K7130-1999 Method A.

[0289] (Melting point) 5 mg of the sample (specifically, biaxially oriented polyester film) was heated from 25°C to 320°C at a rate of 10°C / min using a differential scanning calorimeter (Shimadzu Corporation "DSC60"), and the melting point was determined by the main peak top temperature of the endothermic curve associated with melting.

[0290] (Tensile strength) A 15mm wide, 100mm long test specimen was cut from a biaxially oriented polyester film. Following JIS K 7127, the specimen was pulled using a tensile testing machine (Shimadzu Corporation's "Autograph AG-I") at a gauge length of 50mm and a tensile speed of 200mm / min. The tensile strength, i.e., tensile fracture strength, of the specimen was calculated from the resulting stress / strain curve. This procedure was used to determine the tensile strengths in the MD (i.e., 0° direction), 45° direction, TD (i.e., 90° direction), and 135° direction.

[0291] (Thermal shrinkage rate) A test specimen measuring 10 mm in width and 250 mm in length was cut from a biaxially oriented polyester film. A pair of marks (i.e., a pair of gauge lines) were marked along the length of this specimen at 200 mm intervals, and the distance between the gauge lines was measured under a tension of 5 gf. This specimen was then heat-treated at 150°C for 30 minutes under no load, and the distance between the gauge lines was measured again. From these measurement results, the thermal shrinkage rate was calculated using the following formula. Thermal shrinkage rate (%) = {(AB) / A} × 100 Here, A is the distance between gauge marks before heat treatment, and B is the distance between gauge marks before heat treatment. The thermal shrinkage rates of MD and TD were determined using this procedure.

[0292] (Color B) * value) Ten biaxially oriented polyester films were stacked and placed in a colorimeter (ZE2000, manufactured by Nippon Denshoku Industries Co., Ltd.), and color b was measured using the reflection method.* The value was calculated. Color b per 1 μm thickness * The value was calculated using the following formula. Color b per 1 μm thickness * value =(Color b of 10 layers of biaxially oriented polyester film) * (Value) / (10 × thickness of biaxially oriented polyester film)

[0293] (Surface crystallinity) FT-IR ATR measurements were performed on both the corona-treated and untreated surfaces of a biaxially oriented polyester film under the following conditions. Specifically, spectra were obtained using the total internal reflection attenuation method with a Fourier transform infrared spectrophotometer. FT-IR: Bio Rad, DIGILAB FTS-60A / 896 Single-reflection ATR attachment: golden gate MKII (SPECAC made) Internal reflective element: Diamond Incident angle: 45° Resolution: 4cm -1 Total number of times: 128 The surface crystallinity is 1340 cm². -1 Absorption appearing in the vicinity, and 1410cm -1 Intensity ratio of absorption appearing nearby (1340cm) -1 Strength / 1410cm -1 Calculated based on the intensity of the force. 1340cm -1 The absorption observed in the vicinity is due to the bending vibration of the CH2 (trans structure) of ethylene glycol. Meanwhile, at 1410 cm² -1 The absorption observed in the vicinity is unrelated to the crystal structure or orientation.

[0294] (Piercing strength) The puncture strength of 5cm square test pieces cut from biaxially oriented polyester film was measured in accordance with JIS Z1707 using a digital force gauge (IMADA Corporation "ZTS-500N"), an electric measuring stand (IMADA Corporation "MX2-500N"), and a film puncture test jig (IMADA Corporation "TKS-250N"). Based on the puncture strength obtained from this measurement (i.e., the puncture strength of the biaxially oriented polyester film), the puncture strength per 1 μm thickness was also calculated.

[0295] (Lamination strength) A laminate was fabricated by dry lamination using a two-component urethane-based curing adhesive (specifically, an adhesive formulated with Mitsui Chemicals, Inc.'s "Takelac® A525S" and Mitsui Chemicals, Inc.'s "Takenate® A50" in a 13.5:1 (mass ratio)) to bond a 70 μm thick unoriented polypropylene film (Toyobo Co., Ltd.'s "P1147") as a polyolefin sealant layer to the corona-treated side of a biaxially oriented polyester film, followed by aging at 40°C for 4 days. The peel strength (N / 15mm) of the bond between the corona-treated side of the biaxially oriented polyester film and the polyolefin resin layer was measured for a 15 mm wide, 200 mm long test piece cut from this laminate. The peel strength was measured under conditions of 23°C and 65% relative humidity using a Toyo Baldwin Co., Ltd. "Tensilon UMT-II-500" tensile strength gauge at a tensile speed of 20 cm / min and a peel angle of 180 degrees.

[0296] (Maximum casting speed) Unstretched films were prepared by gradually changing the rotation speed of the cooling drum, and the presence or absence of pinner bubbles was visually determined using a polarizing plate (manufactured by Nishida Kogyo Co., Ltd.). The maximum casting speed was then determined from the maximum rotation speed at which no pinner bubbles were observed.

[0297] (Film forming property) The film-forming properties of biaxially oriented polyester films were evaluated according to the following criteria. ○: No rupture occurred for more than 60 minutes. In other words, continuous film formation for more than 60 minutes was possible. △: At least one fracture occurred between 30 and 60 minutes. ×: Broken at least once in less than 30 minutes.

[0298] <Raw material: Polyester> (Polyester B) The separated and collected PET bottle bales were crushed while circulating them in a wet crusher with a washing solution (specifically, a washing solution made by adding 500g of liquid dish soap to 1000 liters of water). A specific gravity separator connected to the wet crusher separated heavier foreign matter such as metal, sand, and glass, and the flakes were extracted from the upper layer. These flakes were rinsed with pure water and dehydrated by centrifugal force. The recovered flakes were obtained using this procedure. 30 kg of molten, undried recovered flakes were mixed in a stirred autoclave with a preheated mixture, specifically a mixture of 150 kg of ethylene glycol and 150 g of zinc acetate dihydrate. Dilutions with lower boiling points than ethylene glycol, such as water and acetic acid, were then removed. The mixture was then reacted at a temperature of 195°C to 200°C for 4 hours using a reflux condenser. After the reaction was complete, the reactor contents were cooled to a temperature of 97°C to 98°C, and then hot filtration was performed using a filter to remove suspended solids and precipitates. The filtrate was further cooled to confirm that the crude BHET was completely dissolved, and then the filtrate was passed through an activated carbon bed and then an anion / cation exchange mixed bed at 50°C-51°C for 30 minutes. In other words, it underwent a pre-purification treatment. The pre-purification liquid was charged into a stirred autoclave, and the excess ethylene glycol was distilled off under atmospheric pressure to obtain a molten concentrated BHET. The molten concentrated BHET was allowed to cool naturally while being stirred under a nitrogen gas atmosphere, and then removed from a stirred autoclave to obtain a fine-grained block of concentrated BHET. The fragment blocks were heated to 130°C and melted, then supplied to a thin-film vacuum evaporator using a metering pump, evaporated, and cooled and condensed to obtain purified BHET. 2650 kg of this purified BHET was supplied all at once to a dissolution tank purged with nitrogen, and after purging with nitrogen again, dissolution was carried out at a dissolution tank temperature of 150°C. After dissolution was complete, the temperature of the dissolution tank was raised to 230°C over 30 minutes while stirring. 2650 kg of the obtained BHET solution was transferred to a polycondensation reactor, to which 300 ppm antimony trioxide, 170 ppm cobalt acetate, 55 ppm phosphoric acid, and 0.3 wt% titanium dioxide were added relative to the amount of PET to be obtained (approximately 2000 kg of PET can be obtained from 2650 kg of BHET). The temperature of the polycondensation reactor was gradually raised from 230°C to 290°C while stirring at 10-40 rpm, and the pressure was reduced to 40 Pa. After reaching the predetermined stirring torque, the polycondensation reactor was purged with nitrogen to return to atmospheric pressure and stop the polycondensation reaction. The solution was discharged in strand form, cooled, and immediately cut to obtain chip-shaped polyester. Following this procedure, a chemically recycled polyester, i.e., polyester B, with an intrinsic viscosity of 0.59 dl / g was obtained.

[0299] (Polyester A) Polyester B (i.e., chemically recycled polyester with an intrinsic viscosity of 0.59 dl / g) was continuously supplied to a crystallization apparatus and crystallized at 150°C. After crystallization, it was supplied to a dryer and dried at 130°C for 10 hours. The dried polyester B was sent to a preheater and heated to 180°C before being supplied to a solid-phase polymerization apparatus. The solid-phase polymerization reaction was carried out at 190°C for 24 hours under nitrogen gas to obtain chemically recycled polyester, i.e., polyester A, with an intrinsic viscosity of 0.79 dl / g.

[0300] (Polyester C) Except for changing the time for the solid-phase polymerization reaction from 24 hours to 50 hours, a chemically recycled polyester, i.e., polyester C, with an intrinsic viscosity of 0.83 dl / g was obtained using the same method as for polyester A.

[0301] (Polyester D) After rinsing out foreign matter such as remaining beverage from beverage PET bottles, flakes were obtained by crushing the beverage PET bottles. The flakes were washed by mixing them with a 3.5% by mass sodium hydroxide solution and stirring at a flake concentration of 10% by mass, 85°C, and 30 minutes (i.e., alkaline washing was performed). The flakes removed after alkaline washing were washed again with distilled water at a flake concentration of 10% by mass, 25°C, and 20 minutes by stirring. This washing was repeated two more times, with the distilled water being changed each time. After washing, the flakes were dried and melted in an extruder, and foreign matter was filtered out by passing the extruded material through a filter. Filters were installed in the extruder up to the third stage, with progressively smaller mesh sizes. The mesh size of the third stage filter was 50 μm. Using this procedure, mechanically recycled polyester, i.e., polyester D, with an intrinsic viscosity of 0.69 dl / g was obtained.

[0302] (Polyester E) As polyester E, i.e., fossil fuel-derived polyester, we used a polyester (manufactured by Toyobo) with an intrinsic viscosity of 0.62 dl / g and a terephthalic acid / ethylene glycol ratio of 100 mol% / 100 mol%. In other words, we used homopolyethylene terephthalate (i.e., homoPET) with an intrinsic viscosity of 0.62 dl / g. For the sake of clarity, we should note that both the terephthalic acid and ethylene glycol were derived from fossil fuels, not from used polyester products.

[0303] (Polyester F) When the esterification reaction vessel was heated to 200°C, a slurry consisting of 86.4 parts by mass of terephthalic acid and 64.4 parts by mass of ethylene glycol was charged in, and while stirring, 0.017 parts by mass of antimony trioxide and 0.16 parts by mass of triethylamine were added as catalysts. The temperature was then increased, and the pressurized esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240°C. Subsequently, the pressure in the esterification reaction vessel was returned to atmospheric pressure, and 0.071 parts by mass of magnesium acetate tetrahydrate, followed by 0.014 parts by mass of trimethyl phosphate, were added. After raising the temperature to 260°C over 15 minutes, 0.012 parts by mass of trimethyl phosphate, followed by 0.0036 parts by mass of sodium acetate, were added. Fifteen minutes after these additions, 3.0 parts by mass of ethylene glycol slurry containing amorphous silica particles with an average particle size of 2.7 μm was added based on particle content. The obtained esterification reaction product was transferred to a polycondensation reaction vessel, and a polycondensation reaction was carried out under reduced pressure at 280°C to obtain polyester F with an intrinsic viscosity of 0.61 dl / g. Here, the ethylene glycol slurry of amorphous silica particles described above is a slurry obtained by mixing amorphous silica particles with ethylene glycol, dispersing them in a high-pressure disperser, then centrifuging to remove 35% of the coarse particles, and finally filtering it through a metal filter with a mesh size of 5 μm. For the record, both terephthalic acid and ethylene glycol were derived from fossil fuels, not from used polyester products.

[0304] (Polyester G) The esterification reaction vessel was heated to 200°C, at which point a slurry consisting of 86.4 parts by mass of terephthalic acid and 64.4 parts by mass of ethylene glycol was added. While stirring, 0.025 parts by mass of antimony trioxide and 0.16 parts by mass of triethylamine were added as catalysts. The reaction was then heated further, and the pressurized esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240°C. Subsequently, the pressure in the esterification reaction vessel was returned to atmospheric pressure, and 0.34 parts by mass of magnesium acetate tetrahydrate, followed by 0.042 parts by mass of trimethyl phosphate, were added. After raising the temperature to 260°C over 15 minutes, 0.036 parts by mass of trimethyl phosphate, followed by 0.0036 parts by mass of sodium acetate, were added. The obtained esterification reaction product was transferred to a polycondensation reaction vessel, and after gradually raising the temperature from 260°C to 280°C under reduced pressure, the polycondensation reaction was carried out at 285°C. After the polycondensation reaction was completed, the product was filtered through a stainless steel sintered filter with a pore size of 5 μm (initial filtration efficiency of 95%) to obtain polyester G with an intrinsic viscosity of 0.62 dl / g. It should be noted that neither terephthalic acid nor ethylene glycol were derived from fossil fuels, not from used polyester products.

[0305] [Table 1] A supplementary explanation is provided for Table 1. TPA is an abbreviation for terephthalic acid. EG is an abbreviation for ethylene glycol. IPA is an abbreviation for isophthalic acid. In the TPA, EG, and IPA columns, "-" indicates that the measurement was not taken. Mg indicates the magnesium compound content based on magnesium atoms. This content is the mass of the magnesium compound based on magnesium atoms relative to the mass of the polyester (i.e., mass of magnesium compound based on magnesium atoms / mass of polyester). Note that here, only the magnesium compound content among alkaline earth metal compounds is shown. This is because the raw polyester did not contain any alkaline earth metal compounds other than magnesium compounds (or it could be said that they were below the detection limit). P indicates the phosphorus compound content based on phosphorus atoms. This content is the mass of phosphorus compounds based on phosphorus atoms relative to the mass of polyester (i.e., mass of phosphorus compounds based on phosphorus atoms / mass of polyester).

[0306] As shown in Table 1, among polyesters A, B, and C, polyester C had the highest intrinsic viscosity and the lowest amount of low molecular weight components. Polyester B had the lowest intrinsic viscosity and the highest amount of low molecular weight components. In other words, the higher the intrinsic viscosity, the lower the content of low molecular weight components.

[0307] Although polyester B (i.e., chemically recycled polyester) had a lower intrinsic viscosity than polyester E (i.e., fossil fuel-derived polyester), its content of low molecular weight components was about the same as polyester E.

[0308] On the other hand, polyester D (i.e., mechanically recycled polyester) had a higher intrinsic viscosity than polyester E (i.e., fossil fuel-derived polyester), but it contained more low molecular weight components than polyester E.

[0309] <Example 1> A three-layer biaxially oriented polyester film was fabricated using three extruders. To form the base layer, i.e., layer B, of the biaxially oriented polyester film, 50.0% by mass of polyester A, 42.0% by mass of polyester E, and 8.0% by mass of polyester G were used. On the other hand, to form the pair of surface layers, i.e., the pair of A layers, of the biaxially oriented polyester film, 50.0% by mass of polyester A, 39.0% by mass of polyester E, 3.0% by mass of polyester F, and 8.0% by mass of polyester G were used. The film fabrication procedure is described below. The raw polyester for forming layer A was dried and supplied to the first and third extruders, where it was melted at 285°C. The raw polyester for forming layer B was dried and supplied to the second extruder, where it was melted at 285°C. The molten polyester was guided from each extruder to a T-die, where it was laminated in the order of layer A / layer B / layer A (thickness 1 μm / 10 μm / 1 μm). The laminated film was then extruded from the T-die and cooled and solidified in a casting drum, i.e., a cooling drum, with a surface temperature of 25°C. At this time, the film extruded from the T-die and before contact with the cooling drum was charged with a wire-shaped electrode with a diameter of 0.15 mm. The casting speed was 70 m / min. An unstretched film was produced using this procedure. The unstretched film was heated to 120°C with an infrared heater and then stretched once in the longitudinal direction (i.e., MD) at a stretching ratio of 4.0 times. Next, the material was stretched in the width direction (i.e., TD) using a tenter-type transverse stretcher at a preheating temperature of 120°C, a stretching temperature of 130°C, and a stretching ratio of 4.2 times. It was then heat-set at 245°C and subjected to a 5% heat relaxation treatment in the width direction. The length of the width-direction stretching zone was 12.2 m, and the width-direction stretching speed (i.e., TD stretching ratio) was 122.66% / second. Subsequently, of the pair of A layers, the A layer in contact with the cooling drum was subjected to a heat treatment of 40 W·min / m 2 After performing corona treatment under these conditions, the material was wound into a roll using a winder. Following these steps, a master roll of biaxially oriented polyester film with a thickness of 12 μm (length 60,000 m, width 8,000 mm) was obtained. Biaxially oriented polyester film was unwound from the master roll, slit into 800mm widths, and while applying surface pressure with a contact roll and tension with a twin-axis turret winder, the slit biaxially oriented polyester film was wound into a roll on a 6-inch (152.2mm) diameter core. A biaxially oriented polyester film was obtained using this procedure.

[0310] <Examples 2-5 and Comparative Examples 1-3> Biaxially oriented polyester films were prepared in the same manner as in Example 1, except that the mixing ratio of the raw polyesters and the film-forming conditions were changed according to the formulations in Table 2. The casting speed was 70 m / min in all of these examples. In all of these examples, the length of the widthwise stretched zone was 12.2 m, and the widthwise stretching speed (i.e., TD stretching ratio) was 122.66% / second.

[0311] <Example 6> An unstretched film was obtained in the same manner as in Example 1, except that the mixing ratio of the raw polyester was changed according to the formulation in Table 2. The casting speed was 70 m / min. The ends of the unstretched film were gripped with clips on a tenter-type simultaneous biaxial stretcher, and after running it through a preheating zone at 120°C, it was simultaneously biaxially stretched at 130°C with a length of 4.0 times in the longitudinal direction (i.e., MD) and a length of 4.2 times in the width direction (i.e., TD). Next, with a widthwise relaxation rate of 5%, it was heat-treated at a temperature of 245°C, cooled to room temperature, and wound up to obtain a biaxially oriented polyester film with a thickness of 12 μm.

[0312] [Table 2] Let me provide some supplementary information about Table 2. The "mixing ratio" listed in Table 2 is shown as a value when the total mass of the raw polyester materials used to form the target layer is taken as 100% by mass. For example, for layer B in Example 1, it indicates that out of the total mass of polyesters A, E, and G used to form layer B (100% by mass), polyester A accounted for 50% by mass. The silica content is the mass of silica relative to the mass of the target layer (i.e., the mass of silica / the mass of the target layer). The mass of the target layer refers to the total mass of the raw materials (e.g., polyester or particles) used to form the target layer. "CRPET" is a general term for polyesters A, B, and C. Mg indicates the magnesium compound content on a magnesium atom basis. This content is the mass of the magnesium compound on a magnesium atom basis relative to the mass of the biaxially oriented polyester film. P represents the phosphorus compound content based on phosphorus atoms. This content is the mass of the phosphorus compound based on phosphorus atoms relative to the mass of the biaxially oriented polyester film.

[0313] By replacing 50% by mass of polyester E (i.e., fossil fuel-derived polyester) with polyester D (i.e., mechanically recycled polyester), the content of low molecular weight components becomes excessively high, resulting in color b of the biaxially oriented polyester film. * The values ​​also became excessively high (see Comparative Examples 1 and 2).

[0314] By replacing 80% by mass of polyester E (i.e., fossil fuel-derived polyester) with polyester C (i.e., chemically recycled polyester with an intrinsic viscosity of 0.83 dl / g), the intrinsic viscosity became excessively high, and the content of low molecular weight components became excessively low. As a result, the film broke during stretching (see Comparative Examples 1 and 3).

[0315] On the other hand, by replacing some of the polyester E (specifically 50% by mass, 20% by mass, and 80% by mass) with polyester A (i.e., chemically recycled polyester with an intrinsic viscosity of 0.79 dl / g), a biaxially oriented polyester film can be manufactured without breakage, and moreover, color b * The values ​​were reduced (see Comparative Example 1 and Examples 1-3). Even with simultaneous biaxial stretching, biaxially oriented polyester films could be manufactured without breakage (see Example 6).

[0316] By replacing some of the polyester E (specifically 50% by mass, 80% by mass) with polyester B (i.e., chemically recycled polyester with an intrinsic viscosity of 0.59 dl / g), biaxially oriented polyester films can also be manufactured without breakage, and moreover, color b * The values ​​were reduced (see Comparative Example 1 and Examples 4 and 5). [Industrial applicability]

[0317] Since this invention relates to a biaxially oriented polyester film, it has industrial applicability. [Explanation of symbols]

[0318] 8...Biaxially oriented polyester film, 81...First layer, 82...Second layer, 83...Third layer, 9...Laminate, 11...Printed layer, 21...Sealant layer, 22...Sealant layer, 31...Inorganic thin film layer, 32...Anchor coat layer, 33...Protective layer, 51...Substrate layer, 61...Intermediate layer

Claims

1. Biaxially oriented polyester film and Adhesive layer and / or anchor coat layer, Including a sealant layer, The biaxially oriented polyester film includes chemically recycled polyester, In the molecular weight distribution curve obtained by gel permeation chromatography of the biaxially oriented polyester film, the area ratio of the region with a molecular weight of 1000 or less is 1.9% or more and 4.5% or less of the total peak area. Laminated structure.

2. Color b per 1 μm thickness of the biaxially oriented polyester film ＊ The laminate according to claim 1, wherein the value is 0.067 or less.

3. The laminate according to claim 1, wherein the content of the chemically recycled polyester in the biaxially oriented polyester film is 20% by mass or more.

4. A packaging container comprising a laminate according to any one of claims 1 to 3.

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